Do the animals in Animal Farm behave like humans? Why?

Yes, the animals are more or less behaving like humans. This is because Orwell wrote the story to illustrate in very simple terms, term that the average person could grasp, how political movements originally based on ideals of justice and fairness can be hijacked by those hungry for power. The specific reference point is the Russian Revolution and its aftermath, with Napoleon representing Stalin and Snowball Trotsky, but the implications are broader. Orwell hopes his audiences will see how they can be like the innocent animals in the story, duped when the "pigs" (in the broadest sense representations of power-hungry people) manipulate language and violence to serve their own agendas. Language was important to Orwell and he wanted to show us, as humans, how important it is to carefully examine what is being said to us to make sure it makes sense and that, under the guise of protecting our rights, words aren't twisted to steal our rights. By using animals, which provided some distance from humans, Orwell hoped to make crystal clear the danger of power and propaganda.