There is no such thing as a heterosexual man or woman who would date or have sex with a transwoman or transman (respectively). Likewise, there is no such thing as a gay man or woman who would date or have sex with a transman or transwoman (respectively) That's my point; this is called bisexuality.

Most people don't really call it bisexuality. If they'd have sex with a post-op trans person they'd still be called heterosexual and homosexual respectively by most people. For pre-op trans people it's more complicated but as long as they aren't willing to have sex with cis people of the same sex, again, no one uses bisexual to refer to them, at most "queer" or maybe "bicurious" or "straight/gay with a weird fetish".

Bisexual almost always refers to attraction to cis men and women (and maybe more), not one of the two and trans people. Let's keep it like that.

hdf jfskldaj fgdjhf hhshg gghahsgag <- I just wrote something very important here. I don't care if you don't understand what it says because we don't need to "preserve definitions".

Yet it could have meant something hundreds of thousands of years ago and if we preserved definitions I may have understood. Yet we saw that there was no need to preserve definitions and now we use another set of letters to mean that same thing.

There's no need to preserve definitions just for the sake of pleasing a dictionary, it's important that they are clear, consistent and that the listener understands what we have to say. In that case, if you're attracted to cis women and trans/non-binary/androgynous/whatever people but not to cis men and you present yourself as bisexual everyone's gonna be confused. It's better to just explain what you are by that point since we don't have a specific word for that but when 99% of people hear bisexual they think "attraction to men and women".