In IMAX and 3D, the new Disney version of “The Jungle Book” is a technological marvel. Never have computer-generated animals looked so realistic and believable. In fact, they are so convincing that it comes as something of a shock when they suddenly start speaking.

That initial disorienting shock, however, eventually wears off and by the movie’s end, the various animals’ voices seem as natural as their fur, hide or feathers.

So magical and precise is their animation that you don’t even realize that these creatures, whether they be panthers, tigers, wolves, bears, snakes, great apes, peacocks, mice or elephants, are all actually more expressive than real animals.

Disney’s computer wizards have imported complex human expressions into animal faces, so we can “read” these animals better than we ever could their natural counterparts.

But the brilliance of this digital accomplishment has its downside. The lone human actor in this jungle extravaganza, 12-year-old newcomer Neel Sethi who plays Mowgli, can’t help but suffer by comparison.

He’s great at portraying wide-eyed innocence but he’s not enough to carry a full-blown movie. I don’t want to be too harsh on a first-time child actor, but I honestly think the movie would have been stronger if he too had been computer-generated. Too often Mowgli is a blank slate to whom things happen.

But to be fair, that might be as much a structural problem with the film as it is an acting flaw. This version of “The Jungle Book,” much like the original 1967 animated feature, doesn’t have strong narrative cohesiveness.

Mowgli is an orphan boy who’s been raised by wolves in the jungle. When a Bengal tiger named Shere Khan threatens Mowgli’s life, it’s decided the boy needs to escape the jungle for his own safety.

The ensuing adventure is more episodic than plot-driven, with Mowgli having a string of random encounters with random jungle creatures, some dangerous, others friendly, and none of them particularly compelling.

What works in this movie is not so much what the animals do as how they look and move and speak. The voice work is every bit as spectacular as the animation, with Idris Elba as the villainous tiger, Christopher Walken as an angry King of the Apes, Scarlett Johansson as the deadly python Kaa, and Bill Murray as the lazy bear Baloo doing particularly fine work.

The original Disney movie was a G-rated musical but this version is a different kind of beast. It definitely earns its PG rating, since it’s infinitely scarier than the first film. In fact, there are so many realistic close-ups of rampaging tigers, panthers and bears that it could traumatize small children.

And as for songs, this version adopts and adapts the original’s two most popular hits, “The Bare Necessities” and “I Wanna Be Like You.” When Mowgli and the friendly bear Baloo sing the first song, the river-swim setting and the happy-go-lucky tone are strikingly similar in both movies.

That can’t be said for “I Wanna Be Like You,” however. In this new movie, King Louie is a much more terrifying King of the Apes — part King Kong, part Godfather, and part Kurtz from “Apocalypse Now.” He’s a powerful creation but when he starts singing that jazzy swing number, it not only ruins the mood, it breaks the spell the animators had so carefully spun. It’s a surprising mis-step in an otherwise technically stunning movie.

Ultimately, this new Jungle Book is like a trip to a world-class zoo. It’s not strong on story, but wow, those animals are amazing.