@Theaetetus,
Allegory, or any sort of figurative language, takes practice to understand. This is a serious problem; this is part of the reason why so many honestly faithful people misread their scripture to disastrous results, this is part of the reason why people are having an increasingly difficult time understanding spiritual literature.
I'm speaking about myself as much as anyone else. I was once a very militant atheist, and the problem was that I simply did not understand figurative language very well. Now, that's not to say that atheists just don't understand figurative language, which is obviously not true. But for me, figurative language took time. I still have a long way to go.
To the point, though, Animal Farm is allegory. I know the whole thing was a joke, but none the less, I think most people recall religious literature when allegory is mentioned. I certainly do this, thinking of Dante and
The Monkey King. But political allegory, as a genre, has a great deal of potential. Looking at modern literature, I think the genre has really exploded with Animal Farm and other texts like The Lord of the Rings.