This newest feature spinoff from the Lego universe, a much simplified version of a long-running animated TV series, is essentially a spoof of a “Power Rangers” season, with a father-son estrangement added as a plot element. “The Lego Ninjago Movie” isn’t as consistently amusing as either “The Lego Movie” or “The Lego Batman Movie,” but it has its moments.

The script, credited to no fewer than nine scribes, is bookended by live-action segments, vaguely reminiscent of the opening and closing of “The Forbidden Kingdom,” in which a cute young boy (Kaan Guldur) wanders into a Chinese curio shop run by an elderly fellow (Jackie Chan) who—seeing the kid’s loneliness—takes his well-worn Lego figure and spins a tale of heroism about it for him. Segue to the Lego city of Ninjago, a happy place overall but for the fact that it’s constantly being attacked by the arrogant warlord Garmadon (voiced by Justin Theroux) from his floating offshore volcano (which he also employs to dispatch generals who displease him—some of whom will show up later at an awkward time).

Ninjago is defended by a group of color-coded teen ninjas in their huge mechs. Their leader is Green (Dave Franco), and his five companions are Red (Michael Pena) Black (Fred Armisen), Gray (Abbi Jacobson), Blue (Kumail Nanjiani) and White (Zach Woods), the last actually an android. Except for Green, each has an elemental power attached to his or her color—fire, earth, water, lightning and ice, respectively, and together they are mentored by elderly Master Wu (Chan), Garmadon’s understandably estranged brother.

The Ninjago public adores the ninjas, but unknown to them, Green is actually Lloyd, the son of Garmadon who is therefore treated as a pariah by everyone but Wu, his five ninja colleagues and his mother (Olivia Munn). Garmadon, meanwhile, has ignored the kid for sixteen years, leading Lloyd to be understandably perturbed too.

When Garmadon attacks again in an impenetrable super-suit, Lloyd breaks the rules by purloining Wu’s “Ultimate Weapon” to use against him. It turns out to be a simple laser-pointer that, unfortunately, invites an even greater threat to the city—a giant (live action) cat called Meowthra, which predictably attacks anything toward which the laser is pointed. Matters get worse when Lloyd loses the device to Garmadon, who takes over the city. The only hope is for Wu and the ninjas to proceed deep into a dangerous forest to seek the “Ultimate Ultimate Weapon,” which turns out, of course, to lie within them. Garmadon eventually joins them, and along the way bonds with Lloyd. But are his evil ambitions truly quelled by the experience?

The essential problem with the movie is that, to be perfectly frank, the heroic figures are generally bland and uninteresting. Chan’s Wu has a few good moments (as when he toots “It’s a Hard-Knock Life,” from “Annie,” to Lloyd on his flute), but Franco’s Lloyd is a colorless fellow, and none of the other ninjas are characterized except in the most sketchy fashion, nor do the actors add much beyond the obvious.

The compensation is Theroux’s villain, a supremely arrogant but singularly inept guy who gets almost all the good lines and bits of business (like his demonstration of the benefits of having four arms). There’s a strong Darth Vader vibe to his outfit, which only accentuates the “Star Wars”-ish father-son plot. Apart from that, though, Garmadon is reminiscent of the obliviously goofy self-confidence that marked Lego’s Batman, which is almost as enjoyable now as it was then. The Meowthra episodes are also fun, though it’s obviously adults rather than kids who will be able to recognize the reference to old Japanese sci-fi movies like “Mothra.”

It also helps that “The Ninjago Movie” boasts colorful computer-generated animation, though the battle sequences (even in 2D format) are visually rather messy (in 3D, they will probably be even more muddled).

In sum, this is a genial but undercooked Lego product, one that tries hard to apply the recipe of the brand from previous films—smart dialogue and witty visuals—to an inferior story, and only sporadically succeeds. But even Pixar nods, so there is hope that the Lego folks can recapture the full magic in future efforts.