what is the symbolic/ interpertive meaning behind the animals vs. the humans?

The animals each represent a different kind of human; the pigs, for example, being the most intelligent are the ones that run the society and should be the best leaders. Napoleon, however, shows how intelligence can be perverted. The sheep are blindly led by the leaders and would do whatever the leaders tell them with no thought. The chickens represent those whose labor is perverted by the leaders and who, even though they try to revolt, are ultimately punished. Boxer represents the hard working man whose labor helps make a country great; in the end, the leaders throw him away when he has outlived his usefulness.