Fantastic Planet

In the distant future, the gargantuan blue humanoid Draags have brought human beings (who are called Oms as a play on the French word for "man", homme) from Earth to the planet Ygam, where they maintain a technologically and spiritually advanced society. The Draags consider Oms animals, and while they keep some as pets, others live in the wilderness and are periodically slaughtered by the Draags, who wish to control their population. Draags have much longer lifespans than Oms, but reproduce much less. Read more on Wikipedia.