Outside of satire, Animal Farm does include humor. In essence, the whole idea of animals taking over a farm is humorous. Superficially, if one is to disregard the underlying meaning of the story, one could find the tale itself humorous. The fact that animals are able to drive off the farm owner, make rules, establish government, and self-destruct is humorous. If one were to use the animals as symbols of mankind, some may find humor in the fact that Orwell does a wonderful job of mocking mankind and government.
As for the text itself, it is funny that the rules of the farm have to be "dumbed-down" so that everyone can understand them. If this happened in the real world, the real world would most certainly be in trouble.