Some of it is straight-forward. It addresses the time from about 1917-1940s in the USSR. Changing political system. Emergence of a classless society in which some are more equal than others. Two legs good, four legs bad, and the animals that come to rule the roost (the pigs) walk on two legs. The gradual changing of slogans--much in line with Orwell's way of thinking that developed to its maximum in "1984". Orwell had participated in Empier as a police officer in Burma (?), and I suspect much of what he learned/saw there was a later response to the effects of colonialism. However, I am not all that up on Orwell, so best I shush and let those who are more fully address the questions you have.