Who seems to represent the point of view of the author? Which of the animals or people comes closest to Orwell's in Animal Farm?

I would say that the animal that comes closest to representing George Orwell's own point of view is Benjamin, the old donkey.

Benjamin does not have any great hopes for the revolution or, really, for anything else.  He believes that, no matter what, things will pretty much stay the same for the animals.  If they are not being exploited by Farmer Jones anymore, they will be exploited by Napoleon.

Orwell clearly is saying in the book that the animals are no better off after the revolution.  Of all the animals, Benjamin is the one who makes this point more than any other.