It’s official: The era of the superhero film has entered its decadent phase. Five years after “X-Men” revivified the genre and three years after “Spider-Man” rode it into box-office history, superfolk are everywhere, fighting crime, saving the world, and driving global Lycra prices through the roof. It’s to the point where you can hardly swing a cat without some costumed clown striking it with lightning. There are so many of them running around that they need their own school system.

That, at least, is the premise of “Sky High,” a slender, silly Disney offering about the travails of super-teendom that underlines the extent to which the cape-and-tights crowd has lately become a part of our cultural landscape. Soon, no doubt, we will be treated to superhero romantic comedies, superhero terminal-illness tearjerkers, and superhero reality shows that follow the lives of those poor, ordinary souls who never stopped tying sheets around their necks and making believe they could fly.

The hero of “Sky High,” Will Stronghold (Michael Angarano), also pretends to have superpowers, though his plight is all the more awkward given that both his parents are, in fact, super. When they’re not busy selling real estate, Will’s father (Kurt Russell) and mother (Kelly Preston) moonlight as the Commander and Jetstream, two of the most famous heroes in the world. Not wanting to disappoint Dad, Will feigns superstrength using a technique known to geeks since time immemorial: Lie on the weight bench until someone walks in the door, exhale loudly and announce, voice quavering with effort, “two hundred.”

Thanks to his exceptional heritage, Will is enrolled in Sky High, a prep school held aloft in the clouds by the latest in anti-gravity technology. There, he learns that he might be a late bloomer whose superpowers could manifest at any time, or that he might never have superpowers at all. (I’ll give you one guess which.) He also fights bullies, romances the wrong girl, and eventually saves the school from the depredations of his parents’ longtime nemesis, a super-villain who goes by the dubious moniker Royal Pain.

As is probably evident, “Sky High” is a shameless ripoff not only of Pixar’s superlative “The Incredibles,” but also of the “Harry Potter” oeuvre, with superheroes substituted for wizards. Like Harry, Will has two buddies, a sweet but ineffectual boy and a gifted, earnest girl. Like Draco Malfoy, one sinister fellow student has inherited his parents’ foul disposition and dislike of the Stronghold family. And like Hogwarts, on the first day of school Sky High sorts its students into separate groups, though in this case they are the decidedly unequal tracks of “hero” and “sidekick.”

Sadly, if unsurprisingly, “Sky High” lacks the meticulous plotting of J.K. Rowling’s novels, as well as their lurking darkness. The story line is a generic variant of the teen-movie genre, substituting heroes for jocks and sidekicks for nerds, and confirming all the usual lessons. (The pretty-butshy girl is better than the popular bombshell, and so on.) Many, if not most, of the jokes are broad and rather obvious, as when Mr. Stronghold repeatedly laments that he just wants his son to be able to save the world once. And the special effects are strictly third-rate, featuring perhaps the least convincing portrayal of flight since 1950s Superman George Reeves was grounded as a danger to himself and others.

But while “Sky High” may be a low-grade imitation of vastly superior source material, it is nonetheless a reasonably enjoyable one. It is an undisputed law of cinema, after all, that it’s fun to see the popular and arrogant laid low by the meek and dweeby; if that involves a stretchy bully being tied to a pole with his own arms, so much the better. The young actors are affable enough to keep the movie ambling along, with Mr. Angarano – who had bit parts as younger versions of Patrick Fugit’s character in “Almost Famous” and Tobey Maguire’s in “Seabiscuit” – finally getting a role to himself as coming-of-age hero Will.

The adult cast is uneven. Mr. Russell is adequate but unexceptional as Will’s dad, and Ms. Preston fails to quite clear even that hurdle as his mom. Bruce Campbell (of the “Evil Dead” movies) is atypically unfunny as loudmouthed Coach Boomer. And the movie’s signal bit of stunt casting, having ex-Wonder Woman Lynda Carter play Principal Powers, falls so flat it makes you miss the days when she was hawking mail-order contact lenses.

But there are relatively witty supporting performances courtesy of “Kids in the Hall” alumni Dave Foley and Kevin McDonald, who play sidekick supervisor Mr. Boy and swollen brained science instructor Mr. Medulla, respectively. (Trying to enlist the former for a double date, the latter explains, “What if I told you it’s not just her twin, it’s her evil twin.”) Director Mike Mitchell (“Surviving Christmas”) gives the proceedings an “I Love the ’80s” flavor, with a soundtrack featuring covers of alt-rock hits from the period (“Melt With You,” “Voices Carry,” “Save It for Later,” and more).

In the end, it’s “Sky High’s” lack of ambition that enables it to succeed, if only just barely. The movie doesn’t try to dazzle with its special effects, like “Spy Kids,” or impress with its inside references, like “Shrek.” It recognizes that it will never be more than a B-movie, or perhaps even a C+, and that acceptance helps give it a kind of good-natured hokiness. While other movies may strive to become heroes, “Sky High” is refreshingly content to remain a sidekick.