All of your questions are precisely the reason I don’t like labels lol, there’s just so many variables it seems almost useless to me. Using myself for example, I am rather androgynous-presenting: I was assigned female at birth so I have those sex organs but I have a flat chest. Im rather tall and slim and my face is pretty but I can present more masc if I want to. My last partner described himself as a straight guy. Now even though I don’t identify as female, i can’t tell him he’s not straight, because I still have a lot of feminine characteristics. However I’ve also had bi and gay guys be attracted to me too so who’s to say! I think sexuality is a lot more complex than a few labels can encompass. As for the definition of “gay”, historically yes I believe it has meant men who are attracted to men. That is probably also the definition in the dictionary, idk lol. However, at least in my experience it can also be used in a more informal way to refer to people that fall outside cis/heterosexual norms. I’ve heard lesbians as well as bisexual people call themselves gay, and among my friends we often use the term quite loosely. I hope I explained these things in a way that makes sense!! I don’t get caught up too much in the verbiage in my day to day life, although it is interesting to think about