'Furry' started around people who
like having intercourse, particularly orgies, in fursuits.
Like the Chuck E Cheese or Mickey
Mouse type suits, which is why its called 'furry'. It started around the convention circuit, solely coming from sexual activities in the suits, as you could see it would be easy for all these people coming together in
one place to do so. People who frequent conventions remember it starting out. This is what furry means.
It seems to have evolved into any anthropomorphic animal involving any nonsense a person will just invent, you can tell it's just made up. Being interested in anthropomorphic animals is called
fiction. 'Animal Farm' is not a furry book.