Before I start, if anyone accuses me of AI generating the points I make in this post because I'm utilizing what I learned through my special interest in creative writing, I will eat you. I know this is not how my usual posts look, but I'm not going to half-ass this for the sake of upholding my usual lighthearted tone.
I did my best at adding legible image IDs for the screenshots in the alt text. Both are under a post saying "There is no wrong way to be an alterhuman BTW." The screenshots are OP's own words.
I want to say something about this, and what I say here, I will be leaving a comment (or several) saying the same under that post and the comment in the second screenshot.
To start with — and I feel like this should be obvious — you cannot say "There is no wrong way to be alterhuman," and "You're experiences are valid, no matter what, no exceptions," and then turn around and say "But you have to recognize you're in some way human though." It is extremely hypocritical and you are contradicting the exact point you're trying to make.
There are beings who were born nonhuman and have thus never been human at any point in their life. (For us — bodily, as we are plural and have varying alterhuman identities between us — we were born, physically, biologically, an elf and have been an elf our entire life and will die an elf.) There are beings who are biologically nonhuman right down to their organs — a fact that you cannot possibly know just by looking at them or assume just by how you perceive them. And might I add, even if you thought you could, why would you care what species someone's biology aligns with?
There are circumstances where it would be harmful to the individual to reality check or force them to acknowledge that by the outside world they might be percieved as human. Regardless of whether you understand, even regardless of whether you believe them, it is always better to be respectful than to risk causing harm to someone by denying them the right to identify how they want or how they feel is right or correct to their personal lived experiences.
You are not in their body or their brain. You are not experiencing the same things the same way they do. You do not have to right to deny the validity of their experiences or identity no matter what your stance is on the subject. Whether someone's identity is chosen, stemming from delusions, based in a disorder or trauma, physical, biological, psychological, emotional, spiritual, or anything, to quote your post OP, "There are no exceptions. Your experiences, feelings, and identity are valid."
Corrections, additions, and opinions are welcome and appreciated.