David Corenswet, Rachel Brosnahan in DC Adventure

From his breakout as writer-director, Slither, to Guardians of the Galaxy, James Gunn has made it his mission to lighten the oppressive darkness of so much contemporary sci-fi with irreverent humor and the exhilaration of an unabashed genre geek. For his first entry as new co-chair — alongside producer Peter Safran — of DC Studios, Gunn brings his signature approach to Superman. The result is very much a comic-book action-adventure but one with a warm human heart. It reveals an obvious love for Richard Donner’s 1978 event movie headlined by Christopher Reeve, and for 1981’s arguably even better Superman II, without sliding into reverential self-seriousness.

That was one of the weaknesses of Bryan Singer’s joyless and swiftly forgotten 2006 effort, Superman Returns, while by contrast, distancing itself so strenuously from the Donner model was the fatal flaw of Zack Snyder’s turgid Man of Steel in 2013, though that doom-and-gloom saga has its champions. Factoring in the superhero smackdowns and team-ups that have cluttered DC’s output in the 2000s, the new millennium has not been kind to Kal-El, the refugee alien from Krypton created by writer Jerry Siegel and artist Joel Shuster in 1938.

Gunn’s screenplay can certainly be faulted for piling on too many elements, making it at times seem lumpy and overstuffed. But what matters most is that the movie is fun, pacy and enjoyable, a breath of fresh air sweetened by a deep affection for the material and boosted by a winning trio of leads.

David Corenswet makes an outstanding Superman/Clark Kent, his performance loaded with self-irony, charm and poignant vulnerability as he wrestles with doubts as to whether his mission to do good and protect humankind was based on a lie. Corenswet’s funny, scrappy rapport with Rachel Brosnahan’s whip-smart Lois Lane — possibly the sharpest and most captivating interpretation of the ace Daily Planet reporter since Margot Kidder — makes their every scene together a delight.

Nicholas Hoult dials down the cartoonish villainy of many previous Lex Luthors, leaning into the evil genius aspect of the character in ways that heighten the stakes. But although he’s the smartest guy in just about any room, Hoult’s Lex is also petulant and insecure, driven by jealousy over the world’s adoration for Superman as much as by the need to eliminate anything in the way of his nefarious schemes.

The movie opens with a quick primer on the centuries-old history of metahumans on Earth, leading to Superman’s first defeat at the hands of one of them. He’s introduced collapsed and bleeding in the snow, summoning just enough strength to whistle for his trusty dog Krypto, who thunders across the white tundra churning up powder before jumping all over Superman as if it’s playtime, not a call for help.

Krypto, who also sports a red cape but behaves like an undisciplined puppy-school reject, borders on cutesy. But Gunn is the guy who made a genetically engineered talking raccoon and a sentient humanoid tree beloved members of the gang in Guardians of the Galaxy, so Superdog is well within his reach in a movie that, mercifully, goes much lighter on that franchise’s bro-ish humor.

When Krypto finally gets the message and drags the wounded Superman back to his crystalline refuge, the Fortress of Solitude, a team of robot helpers gets to work on repairs. They heal him physically with a blast of sunlight and soothe him emotionally by replaying the partially lost farewell hologram message from his parents, his last remaining link to his since-destroyed home planet.

Identified only by numbers, the custodial droids are a nice touch. The chattiest of them, No. 4 (Alan Tudyk), gets laughs by continually speculating on the human emotions they would be feeling if they could feel.

Back in Metropolis, Superman again gets hammered by the Hammer of Boravia, a hulking, heavily armored mystery figure who appears to have similar powers to Superman and then some. (The character’s identity shouldn’t be too hard to guess for longtime comics aficionados.)

The Hammer rips up much of downtown, causing millions in damages, but shifts the blame by saying the mayhem was a response to Superman’s attack on his country’s armed forces. But Superman claims his actions were to prevent a war in which people were going to die, following Boravia’s attempt to invade the poor neighboring country of Jarhanpur. The shady Boravian president (Zlatko Burić) insists that the Hammer is a vigilante with no ties to his government.

Unsurprisingly, this chaos is being orchestrated by Lex, high up in his glass tower at LuthorCorp, with a Bluetooth headset and a team of black-uniformed techies at keyboards carrying out his commands. He has every conceivable fight move preprogrammed, enabling him to shout numbers at his crew like a football coach calling game plays from the sidelines.

Lex is a tech billionaire very much in the Musk/Zuckerberg mode, but Hoult gives him sufficient ambiguity to blur the lines of his villainy between someone genuinely concerned about humankind in thrall to an alien and someone who just wants absolute power at any price.

Gunn takes the vast canon of Superman lore — from various iterations of the comics to TV shows like Smallville to the Donner films — and treats it like a grab bag, plucking elements from many sources.

That includes Lex’s most valued ally, Angela Spica (María Gabriela de Faría), aka The Engineer, a dark-eyed beauty whose nanite-enriched blood allows her to morph body parts with inky black fluidity into whatever form is required — be it buzzsaw hands or tentacle-like cables that can hack into any computer circuit. That skill proves useful with the Fortress of Solitude’s digital hub, allowing Lex to release a doctored copy of the message from Superman’s parents, replacing the scrambled section with a command to lord over Earth and its people without mercy.

It’s plot points like this that show how superhero sci-fi might intersect with real-world AI concerns — the idea that fabricated information can be circulated to turn a revered public figure into a pariah no longer seems like fantasy. Only slightly less relatable is Lex’s fleet of trained monkeys at computer monitors, flooding social media with falsehoods and conspiracy theories and coming up with damning anti-Superman hashtags that stick.

There’s a lot going on in Gunn’s script, including a Luthor-constructed “pocket-verse” that houses his own cavernous hi-tech prison; Rex Mason, or Metamorpho (played by the wonderful Anthony Carrigan from Barry), a humanoid exploited by Lex for his shifting chemical makeup, which allows him to transform body parts even into Kryptonite; and the metahuman Justice League.

That trio of corporate-backed law enforcers includes tech wizard and man of many cool gadgets Mister Terrific (Edi Gathegi); airborne warrior Hawkgirl (Isabel Merced); and their self-appointed, self-inflated captain Guy Gardner, better known as Green Lantern (a droll Nathan Fillion), who has hands-down the worst bowl cut and dye job in Metropolis.

Paradoxically, the human heart that grounds the story is the alien from Krypton. Corenswet brings such warmth to the role that he anchors the film every time it threatens to veer off into overly busy fantasy. Lex’s sabotage proves so effective that it sparks an existential crisis in Superman, who at his lowest point retreats to the farm of his adoptive parents (Neva Howell and Pruitt Taylor Vince). It’s one of the movie’s loveliest and most affecting interludes.

Corenswet is equally strong as Clark, tempering the usual nerdy awkwardness and giving him more confidence in his role at the Daily Planet, without making him too slick. The chief contributing factor behind his more self-possessed Clark is that Gunn removes the mystery of his dual identity for Lois, departing from the usual story by dropping them three months into a relationship.

It does, however, remain a secret in the newsroom, from cigar-chomping editor Perry White (Wendell Pierce, underused, but always good to see him), Steve Lombard (Beck Bennett) and Jimmy Olsen (Skyler Gisondo). Lois plays along at work, upping the undercurrent of romantic frisson in her flirtatious, teasing banter with Clark, but their one-on-one time in Lois’ apartment is the movie’s stealth weapon.

In one amusing moment, Lois shrugs off his concerns about exposure, suggesting that people are bound to figure it out sooner or later, prompting Clark to respond, “But the glasses?” Brosnahan and Corenswet are especially disarming in a scene in which Clark agrees to sit down and be interviewed by Lois, after she complains about him always getting the “Superman exclusives.” The subtle idea that the Man of Steel is somewhat controlling about his media profile is quite funny.

Gunn also makes an appealing choice by having the Daily Planet team pile into Mister Terrific’s T-craft flight vessel to help rescue Superman and stop an impending disaster. Jimmy, boyish and cocky as ever, proves a real asset thanks to his clandestine connection with Lex’s fashionista, selfie-snapping girlfriend Eve (Sara Sampaio). She’s never identified as the Miss Teschmacher played so divinely by Valerie Perrine in the Donner films, though she’s one and the same, and maybe not as shallow and ditzy as she seems.

A brief but tantalizing appearance of another canonical Superman universe character near the end whets the appetite for an installment coming next year.

Pumped up by DP Henry Braham’s dynamic camerawork, Beth Mickle’s imaginative production design, the effects team’s top-notch CG work and a galvanizing orchestral and synth score by John Murphy and David Fleming that weaves in the immortal John Williams theme, Gunn’s Superman is overloaded, even muddled at times, but relentlessly entertaining. Perhaps its biggest strength is that it sidesteps all the revisionist murk of superheroes onscreen in the last decade or two and reverts almost to an enchanting state of child-like wonder.