I’m having a hard time following your train of thought here. Correct me if I’m wrong, but I’m working off of a couple assumptions based on your post history. You believe that sex determines your gender, and thus that trans women are actually men and vice versa for trans men. Wouldn’t trans people also fall under the category of “men and women” in that case? If gender is binary and can’t be changed, everyone is either a man or a woman. So how are those two categories helpful for distinguishing trans people from people who are not trans? This is why I find cis to be a useful term.