A likable enough, Amblin-esque update to the classic Arthurian legend, “The Kid Who Would Be King” is hardly the first time a group of adolescents have saved England from supernatural harm in a Joe Cornish movie. That said, much of the attitude and originality that drew fans to the irreverent writer-director’s inner-city alien-invasion debut, “Attack the Block” — wherein underdog heroes faced off against fluorescent-fanged beasties from outer space — has gone missing from his eight-years-later second feature, which skews considerably younger and safer than that 2011 cult favorite.

Maybe that’s because the kid in question is bland 12-year-old Alex (Louis Ashbourne Serkis). Polite, white, and thoroughly unexceptional, Alex comes across as an average student in most respects, proving that chivalry is not dead by intervening when best friend Bedders (Dean Chaumoo) is hassled by classmates Kaye (Rhianna Dorris) and Lance (Tom Taylor), two bullies who would no doubt have been sorted into Slytherin if they’d been sent to a more magical boarding school. Oozing menace, Lance reminds the runty do-gooder that he’s the king of Dungate Academy — as if that were a thing thugs say in this day and age.

Next time these two schoolyard villains spot Alex, they chase him into a fenced-off construction site, where the boy slips off a ledge and finds a well-worn sword wedged deep in a block of concrete. Pulling it free without trouble, Alex doesn’t realize that he’s the first person in centuries to have touched Excalibur, which was last brandished by the long-dead Arthur and is now coveted by Morgana (Rebecca Ferguson), an evil, seemingly immortal enchantress who looks like a cross between Walt Disney’s Maleficent — in full-fledged dragon form — and some sort of sexy mandrake, buried deep but armed with tendril-like roots she uses to spy on the world above.

Speaking of Disney, Cornish’s contemporary twist on Knights of the Round Table lore borrows less from medieval literature than it does from Disney’s 1963 animated “The Sword in the Stone,” which was itself adapted from T.H. White’s 20th-century novel “The Once and Future King.” To further simplify which details of the legend the writer-director considers relevant to this retelling, Cornish supplies Alex with a comic-book-style primer that conveniently describes each of the elements he can expect to encounter on his quest — which involves a trek to Tintagel Island in Cornwall (both home of Arthur and the helmer’s namesake).

Since Alex grew up fatherless, raised not by Merlin but by his single mom (Denise Gough), the possibility remains that somewhere in his family line lies a connection to King Arthur. At least, that’s the assumption upon which Alex chooses to accept the seemingly exclusive fate that has been thrust upon him — although unlike White, who conceived Arthur as an orphan of noble origin, Cornish is perfectly fine with Alex’s being ordinary. It’s a charitable attitude to be sure, except that when everybody’s special, no one is (a peculiar tendency that has lately extended to “Star Wars: The Last Jedi,” which implied that a Force-blessed servant boy might one day grow up to take Luke Skywalker’s place, and the final groan-inducing twist of “Glass”).

The one undeniably exceptional character here is Merlin, who switches between three forms with a violent sneeze: Most of the time, he appears as a bright-eyed young man (Angus Imrie) who casts spells using a sequence of finger snaps and flamboyant hand movements that viewers may well attempt to memorize and repeat in the real world. Merlin can become an owl at will, and with a bit more effort, sometimes opts to present himself as Patrick Stewart, who, in just four scenes, significantly boosts how seriously we take the film, which otherwise relies on the charisma of its so-so child actors.

Merlin introduces the element of magic into affairs, the use of which proves as often comic as not, although none of the humor here reaches the laugh-out-loud lunacy Cornish brought to his screenplays for “The Adventures of Tintin” or “Ant-Man.” Rather, so much of his “Kid” script seems worried about how to tick off the various Arthurian elements, awkwardly contorting itself in order to introduce the Lady of the Lake, for instance, while freshening up other aspects with a rather inspired explanation of Stonehenge’s true purpose.

With its retro-video-game score and “Goonies”-style gang of misfit characters, the movie plays like a throwback to Spielberg-produced adventure films of the ’80s. And yet, the premise feels wobbly at best, considering that the movie has no real intention of seeing Alex’s good fortune through to his coronation (what use does England have for a king these days anyway?). Instead, Cornish gives in to the kind of visual effects-heavy set-pieces that fit far more organically in bigger-budgeted movies, as when the souls of fallen soldiers are resurrected as smoldering horsemen, which Alex and his knights must face off against night after night leading up to the CG-intensive finale, as Morgana attempts to steal Alex’s sword by force, with the end game of enslaving all of England.

Cornish never allows “Kid” to get too dark, and by limiting Alex’s army to the fellow students he finds at Dungate Academy, he reveals the rather narrow demographic he had in mind all along. The PG-rated film never puts any human characters in serious peril, making it far too easy for these kids to overpower their enchanted adversaries. By comparison with “Attack the Block,” whose ensemble of accidental heroes had personality to burn, Alex and his friends come off pretty flat. His limited range and relative privilege all too apparent amid an agreeably diverse cast, young Ashbourne Serkis (son of performance capture pioneer Andy Serkis) feels like sidekick material at best, suggesting that a teenage girl or perhaps an up-and-coming actor of color might have made an even more compelling king.

https://variety.com/2019/film/reviews/the-kid-who-would-be-king-review-1203106233/