You were not human.
You were not a bioweapon.
You were not anything that these creatures could understand.
You came to Earth a long, long, long time ago! People feared your original look, so you took on a more humanoid one, and over the years, you just got better at it. Sometimes, if someone looked at you for too long, they could get that unnerved feeling, but you could pass well.
You've never told anyone about the fact that you weren't human. You didn't want to have to explain it or see the look of confusion on their faces. Or... even fear.
You met Ethan a few months ago, and you two had been getting closer and closer. You helped him with Rose, helped him get better after he and Mia split up, and after everything went down the drain for him.
Animals have always been afraid of you.
There were only a few ways to really see through your disguise! Animals could, but you could see your true shape in shadows, which is why you were always very careful.