@ButterflyHatched
I don't think we need to be bound by the historical precedent of what came before, though - in the same way that we don't need to pretend atoms are indivisible, fundamental units of matter anymore. We just need to be clear which definition we are using, and make sure it is the correct model.
You miss the point (several points in fact).
Firstly, the point about history isn't that we can never change, or even that the historic view was even right (in the case of historic sexism, I clearly would say its not). And it's not about who has the "right" definition of womanhood.
It's simply that whether what was historically understood by "woman" was right or wrong, the historic injustices dealt to the people who met that historical description were still real, and they did happen to that group of people and not, for example, the people you now believe women to be.
Do you understand that? They didn't happen to the word Woman, they happened to the people who happened to be under that word at the time.
Similarly, the physical facts of (old definition) womanhood - the vulnerabiliity to rape and other physical abuse, the physical burden of reproduction and the social burden of the assumption of reproduction whether we chose to or not , the on average lower strength and speed, compounded by structural assumptions of male norms - these still exist and still apply to the same people regardless of whether you allow us the name Woman to describe our commonality or not.
And why does that matter today? Because whether right or wrong about "woman", these facts have shaped our culture. There are men who festishise female spaces and violation - that's why there's a market for hidden cams and upskirt videos. There are still men (and women) who believe female people are less suited to the type of work that earns good money, or that we should bear the heavier caring and domestic burden, or that our choices for how to spend our time are never more important than a man's desire for our company, or that if we reject a man we are a stuck up bitch who needs to be taught a lesson, or that our murder is a lesser crime than to feel humiliated by us... this all still happens. They don't check our identity or plot us within a corruscating constellation of statistcially significant correlations, they just do it to us because we meet the criteria for the people to whom they have always done it.
So sure, you may have a deeper, more subtle, just gosh darn righter conception of womanhood than those who foolishly believe their victims to be women based on some old, outdated notions but from the point of view of the victim that makes fuck all difference because these acts of sex-based oppression happen to us not because we meet your new and improved definition but because we meet the definition of sex under which they are constructed.
And here you are with your "oh but things can change, we can have better understanding" and you think that word salad alone, the clvereness of your concepts, is enough to ignore all that, as if by changing the meaning now, all that cultural baggage, all those toxic beliefs, just evaporate. As if we don't need to worry about what men (old meaning) did and still do to women (old meaning), as if just because you changed the definition of "woman" they won't connect us and our bodies to that old idea any more.
And so you allow yourself to appropriate everything that exists for "women", that we need to counter that age old opporession, while you do nothing - nothing - to change the fact that the men (old version) who had those toxic ideas about women (old version) before still have them about us now and will cntinue to act on them regardless of whether you allow us to name our sex Woman or not.
In short - of course I can imagine different ways to think of sex, or to structure society. I can imagine all sorts of better worlds. That's easy.
The hard part, the part that makes this fair, the part you are skipping, isn't where should we go to, it's how do we get there from here in a way that acknowledges the reality of how sexism embedded in our society continues to impact female people on a personal and societal level, and makes sure any social transition deals fairly with female people as well.
And on that, for all your words, you are notably silent.