It was hard for me to read about Boxer since the middle of the story. He has the purest soul and was taken advantage of by the environment.
The brainwashing propaganda in the story is the same as the politicians who forget being a government official, you have to serve the civilians instead of manipulating power to get rich.
The windmills are the pigs' ambition and they sacrifice other animals to achieve their goal. I agree with you that society set a standard for people to follow without caring for the different passions of different people.
We only have one life, and we should live for ourselves once for this only opportunity.