A couple of thoughts occurred to me in reading the original post; several of these having also occurred to others, I add only this: Orwell got the idea of setting his allegory/satire on a farm from a specific incident (presumably the idea of which animals would best represent different "Types" of Humanity and/or different factions/groups in the specific Russian setting came to him pretty quickly too). The incident? He saw a young farm-boy, on foot, "driving" a great Clydesdale cart-horse down a country lane; the boy wasn't beating the horse, just waving a stick as an "encouragement", or threat, and the poor brute was rolling its eyes in fear. Orwell recognised that the horse could have crushed the youth instantly, but it had learned fear, obedience, "I will work harder" as Boxer puts it. "Working people of all nations, unite..."; at least it will be a while before you can't tell the New Boss-Class from the Old, and maybe one day the Revolution will break out of the usual pattern. But then, we come back to "Types" of Humanity.