Derivative as all get out and plainly concocted by a committee, “Epic” is a children’s animated film that is more entertaining and emotional than it has any right to be.

Characters make sacrifices and die, miss their parents and mourn. And we’re touched. At least a little. Hard (if over-familiar) lessons are learned and laughs land on queue. Throw in some truly gorgeous animation, and Blue Sky, the studio that made it, delivers more proof that it has moved on from the junky cash-machine “Ice Age” movies, even if this one doesn’t rise to the charms and wit of “Rio.”

Taking characters from William Joyce children’s novel about “Leaf Men” and “Brave Good Bugs,” a team of writers has borrowed from “Antz” and “A Bug’s Life,” and even “The Spiderwick Chronicles,” for a story about the fairy forces of life in a forest, the Leaf Men (and women) and their allies, in battle with the rotting reptilian bog-dwelling forces of decay.

A dotty scientist has surveillance cameras covering the forest where this struggle is going on and suspects there are little people out there, riding into battle on hummingbirds and crows, armored and armed with bows and arrows.

But it’s his daughter, M.K. (voiced by Amanda Seyfried), who finds the proof. That happens when she’s magically shrunk by the Queen (Beyonce Knowles) and tasked with ensuring that this one lily pod blooms and renews life by the light of the full moon.

M.K. struggles to survive this brave (tiny) new world, where warriors like the rebellious Nod (Josh Hutcherson) and mission-focused Ronin (Colin Farrell) must fend off the reptilian designs of Mandrake (Christoph Waltz), who plans to upset the balance between new life and decay and thus take over the forest.

M.K. is assisted in her quest by a very funny snail and a slug (Chris O’Dowd, Aziz Ansari), who know how to keep the pod alive until it blooms. And they are guided by the daffy six-legged Nim (Steven Tyler), the “scroll-keeper” who sings and studies records from the past to figure out how to carry out the pod-blooming ritual.

The film’s 3-D makes excellent use of depth of field, delivering eye-popping next-generation animation that, among other things, gives the forest and its creatures wonderful shadings and detail, and makes the cartoon humans even more lifelike.

But that’s the sort of thing critics mention when the story is kind of all over the place, a real patchwork of ideas and inventions borrowed from elsewhere.

“Epic” isn’t epic, but it isn’t half bad, either. It’s just that as high as the bar has been raised on this sort of animation, this is more evidence that a strong story is worth more than any next-generation software.