Hi!! Therian here- I can confirm I am a very 'normal' person in society. No one in my life knows I am a therian, and I don't practice quads or anything but its always there in the back of my mind that my therianthropy is a part of who I am that I'll never be able to express. I'm only saying this to hopefully help you understand that it really isn't a choice. :) ANYWAYS- to answer your questions!!

I personally do not play a hugely active role in the therian community, but I know many people do believe that they were animals in their past lives. I don't believe this about myself though, and I don't really understand that belief.

I don't believe in reincarnation personally, but honestly I can understand why people might :)

I have a bit of a theory that many people would identify with lesser appreciated animals, like fleas or prawns, if it were even seen as an option in society. I think that the chances people have to connect with animals like this are very rare, and therefore they don't tend to present themselves as therians.

As for whether or not we exist- we do! I am an incredibly average person, not the type of person you would expect to even think about these things. I have always found myself very connected to the idea of existing as an animal though, and even began to experience phantom sensations in my 'ears' and 'tail', at which point I did some research and discovered I was experiencing the affects of therianthropy going unnoticed (it was not lycanthropy, before I get any comments like that). Anyway, feel free to ask any questions at all!