This is less of a question and more of a statement, but hey, I’ll do my best to give you my input on it, haha.
“Therianthropy is the mythological ability of human beings to metamorphose into other animals by means of shapeshifting. It is possible that cave drawings found at Les Trois Frères, in France, depict ancient beliefs in the concept. The most well known form of therianthropy is found in stories concerning werewolves”
I actually hadn’t heard of this until now, thank you! The term “therian” originally started being used for the comminity back in 1993, on the site ‘alt horror : werewolves’ (don’t quote me on that, though, as I’m not completley sure) and it probably did have something to do with this original definition. Maybe a better word to describe us would be “alterhuman” but that could suggest that we believe we are something other than human, which we do not.
As for the “long debunked and delusional trappings” part, I want to bring up what I actually believe in, and see how different it actually is from other beleifs (although if you believe they are also long debunked and dilusional, then there isn’t much point and you can just scroll on by, haha)
This isn’t the same for all therians, but as the question (well, sort of) was aimed at me, I’ll answer it from my point of view. I believe in reincarnation, and that I was my theriotype/s in a past life, and that as a human, I feel as though they are still a part of me and I identify as it, if that makes sense. The key word there is ‘believe’ - I do not think that it is fact, and I cannot prove it to you, but it is just what I believe in, as some people believe in gods, or in other things.
Thank you for asking! I hope I answered your question, but feel free to ask more if you feel you have more questions :)
Edit - please have a look at ulfrvif’s comment, they describe and explain it better than I did here!