Most of the animals in this work are shockingly ignorant and heartbreakingly gullible. They are too quick to believe what they are told and too easily miss what is really going on. Orwell, in very simple terms, shows us how political and social oppression can occur step-by-step under people's (or animals') noses. The pigs make each little move in the slide toward tyranny look reasonable: of course, they need better food, of course, they need to sleep in a house, why shouldn't they train the dogs, etc. Why not change a word here or there in a slogan, especially to make it easier to remember? Why not deal with the humans? Meanwhile, they are getting a tighter and tighter grip on power, to the point that when the other animals wake up to what is going on (at least those few who do) it is too late.

The sheep are the best representation of a large mass of ignorant people who can be easily manipulated to support whatever those in power want, even if it works against their own interests. Every time some of the other animals start to speak up and push back against the pigs, you can count on the sheep to start their mindless chanting of "four legs good, two legs bad," drowning out all reasoned discourse. Orwell shows how keeping a large group in ignorance supports oppression.

Orwell also shows the problem of bystanders. When the hens take a principled stand about keeping their eggs, none of the other animals know how important it is to support them, making it easier for Napoleon to crush their rebellion.

Orwell, of course, wants us to apply this fable to our own lives and political situation. He doesn't offer any explicit answers, but he does warn us to be very careful with how we use our language, where we place our trust, and with remembering that those in power don't necessarily have the interests of the majority of people at heart.

Throughout the novella, the pigs are the most intelligent animals on the farm and use their superior intellect to their advantage by altering rules in order to give themselves undeserved privileges. Towards the beginning of the story, the pigs become literate and label themselves as "brainworkers" in order to avoid physical labor.

Shortly after Napoleon usurps power, he uses Squealer to spread propaganda and alter the Seven Commandments, cementing his reign and increasing his power. Squealer's articulate, clever grasp on language allows him to present seemingly logical arguments, which confuse and convince the less intelligent animals to support Napoleon. The animals are not able to point out the logical fallacies in Squealer's arguments, and their ignorance allows Napoleon to bend the rules in his favor.

Boxer symbolizes the mindless, naive, hardworking masses, who ignorantly follow deceitful politicians. Boxer demonstrates his blind, unquestionable loyalty to Napoleon throughout the novella as the unscrupulous leader works the massive horse to death. Boxer's favorite slogans are "I will work harder" and "Napoleon is always right." Unfortunately, Boxer's lack of intelligence leads to his demise as he is continually taken advantage of throughout the novella. None of the animals, except Benjamin, are as intelligent as the pigs, and they live oppressed lives under Napoleon's tyrannical leadership. 

Benjamin, the donkey, is a cynic who believes no one can make things better. He represents the cynical intellectual who believes he's above politics, refusing to get involved in trying to change society or government. His ignorance is pride.

Boxer and Clover, the horse, represent the working class. Boxer blindly follows Napoleon while Clover unsuccessfully tries to help the others see reality. Their ignorance is believing the leaders will help them or their own laziness or apathy.

Minimus, the poet, writes a poem and a song for Napoleon. He represents artists who allowed the government to use them to spread propaganda.

Mollie is self-centered, thinking only of herself through the book. She goes back to working for humans because she's only concerned with material things and not ideals, such as freedom.

Moses, symbolic of organized religion, tells stories about Sugarcandy Mountain. He's used to entertain the others. His ignorance is believing in some fairy-tale place where life will be perfect. 

The sheep are the blind followers who do whatever they're told, having no real idea what anything means. They are truly ignorant.

All of the animals characterize some segment of society that allows a totalitarian regime to come about and stay in power because of their ignorance in one way or another.