Conflict is central to the plot of almost every story. Most stories actually have a number of conflicts, which is also true of our daily lives.
Initially, the animals have an external conflict with Farmer Jones. They don’t like his methods and they want to be free of his control. Once they rebel, they have external conflicts with other farmers and then the pigs.
We see some internal conflict also, as the animals begin to question Napoleon’s actions as a leader. They note that things haven’t gotten much better, they are still hungry, and they have to deal with some confusion regarding the basic tenets of Animalism as the pigs try to cover their excesses by making sneaky changes to the commandments.