What is significant about how the animals arrange themselves as they gather to hear Old Major?

Other points
of significance include:

Moses is markedly absent. Moses (as the name
suggests and as you discover later in hearing about a place called SugarCandy Mountain)
represents religion. Faith has been removed from this set of ideas about to be shared.

Benjamin the donkey is introduced as old and cynical and enters as one of the last.
This is important because of what he represents. He has likely seen ideas come and go and get
repeated in life, they are just...