Awwww, okay, thanks.
Well I'll be happy to explain it to you if you're curious. I'm otherkin. There are two big philosophies in the otherkin community about how it works: the neurological group, and the spiritual group.
The neurological otherkin believe that just like trans people, they have an abnormality in their brain that has changed their species affinity from human to something else. They identify as having a human body and brain, but a nonhuman mind within that brain.
The spiritual otherkin believe that certain spiritual experiences they've had explain their identity. Spiritual otherkin often believe they reincarnated from a nonhuman body into a human one. They might have experiences of having a nonhuman astral form while astral projecting.
Personally, I'm an antirealist. I don't think the nature of reality is objective. I think our subjective reality is made up of cultural constructs. I think the idea of species is unscientific and impossible to define by biological characteristics. I believe our social constructs should be manipulated to serve people, instead of the other way around. If we're manipulating people to serve our social constructs, then we're a failed society.