Why do you refer to yourself as an alien?
I use various non-human labels to describe myself because I feel very disconnected from what society expects of me as a human. Between my gender and disabilities, I feel foreign.
My gender feels so distant from existing labels that it feels out of this world. Because of my autism, I had to teach myself how to interact with people, because it's incredibly hard for me to pick up on social queues, tone, body language etc unless I've gotten to know someone specifically. I've also had to teach myself how to act "normal" and create masking techniques as a defence mechanism.
I've often felt like I was an alien pretending/learning how to be human, because it all felt so unnatural for me. So many things that are expected from humans just did not apply to me. I had unusual/conflicting interests growing up, I always had weird or unusual "dream jobs" as a kid, etc.
Society doesn't accommodate for or acknowledge most disabilities, including my autism, CPTSD, chronic pain, and chronic fatigue. Because of this, I always feel left out, which can then trigger my BPD symptoms. There are such little accommodations or considerations for people like me in most social situations, that it makes me feel like I don't belong.
I never felt connected to gender at all as a child. Being raised as a girl, I had so many expectations put onto me that included what I'd like, how I'd dress, how I'd behave, and basically what I wanted. And it seemed like everyone was really able to embrace their gender identity (at the time all I knew of was "boy" and "girl") and what was expected of them, and I never could. At 15, I became aware of non-binary identities, and it answered so many questions! I can now fully embraced with my gender for the first time.
But, society still doesn't acknowledge non-binary identities as a whole, so I still feel forced to confirm to 1 of 2 standards, and sometimes I genuinely have to pick between M and F. It makes me feel as if I don't belong in this world.
As you can see, I get excluded a lot, and that forces me to find or create my own spaces where I DO belong. I've found others like me, and it seriously feels like I've found my 'species' amongst queer and disabled people. It's an incredible feeling. Our communities are so distant from societal norms that it finally gives me space to be myself, AND with others! It feels completely right being distant from society.
And that's why I call myself an alien.
Here's a little meme that works well as a "TL;DR".