That's an interesting theory. I believe the same thing in some aspects, however for some parts I have a different opinion. I do believe in past lives, though. I cannot say my opinion on the matter fully, because I only have experience with therianthropy, and am unsure about opinions on the reasoning behind otherkin and any other nonhuman identity other than therianthropy.
I plan to look further into nonhuman experiences other than therianthropy. Perhaps, if you are okay with it, you could tell me about your experience of having a dragon kintype, and how similar it is to being a therian?