Gender is not some esoteric academic theory. It is simply a fact, one that can be easily shown simply by looking at different cultures and people. Are skirts only feminine? Are women always subservient to men? Are boys always more aggressive than girls? Are they always more violent? There are so many assumptions and customs in our society, based on gender, that have very little if any relationship to a person's sex that it not a question of outlook or philosophy, but simply a matter of observable reality.
The only reason gender was not talked about until recently is the almost universal assumption that everything we believed about the differences in sexes was generic or inborn. That there was no difference between sex and gender.
This is where modern CRT/feminist theory/whatever-you-want-to-call-it is factually wrong about history, both about the term and about social convention. It was a basic assumption of second-wave feminism that
gender roles were essentially social conventions, which included household responsibilities, dress, and participation in society. Obviously a huge part of this was opening up the career option for women and the ability (at the time, encouragement) to choose not to have a family. This was well-known at the time, to the point where it was plainly obvious even to conservatives that obviously long hair being feminine wasn't set in stone anywhere, and wearing pink was not feminine unless you decided it was. In fact this concept was so well-established then that we have to take a step back in the present tense as science informs us that some differences between men and women, even in fashion, life choices, and preferences, are in fact biologically determined and are not merely conventions. So to the extent that we ascribe
nature to these things, it is more true now than it was in the 60's when the concept of plasticity was even stronger in the humanities than it is now for
well-informed people. So that is one thing CRT/whatever is wrong about.
Another thing it's wrong about is that gender wasn't understood until now. And part of this is a language-bending issue. If you're going to use a word in a newly-invented way obviously you'll be able to sell that you've invented the concept you've attached to it, but it's been known not just since the 50's, but
for centuries, that there is some spectrum of masculine/feminine in all people, and that you can have a masculin woman and a feminine man. Back then they just called it 'life' and didn't need an academic term for it. Likewise, there were always people who clearly didn't fit into society, both into gender roles (i.e. women belong in the household, should wear women clothes, etc) and in many other ways. Another difference between then (e.g. Elizabethan England) and now is that back then
no one fit into society, because the differences between people were huge. Now things are narrowed and normalized, so that you might risk feeling sometimes that people are all doing an impression of each other in language use, manner of dress, meme usage, and especially mores and values. On both liberal and conservative fronts I can pretty much script how an argument would go back and forth on a number of topics, and in 9 cases out of 10 a real live person would say exactly the things I've scripted, like a bot. It wasn't like that back then. So to the extent that normality and fitting into gender roles is such a big deal (to the point of a person saying even their sex-at-birth doesn't fit their self-experience), that is also a fairly new thing since I don't think 'feeling normal' was even a thing hundreds of years ago, such that it would be a big deal if someone didn't feel normal. There was no normal, at least not like there is now. This is due to a combination of processed education and socialization, mass media, commerical branding, and even there mere fact of better nutrition and having less of a health gap in the first world. But
people have different internal characteristics along the masculin/feminine axis is not exactly new information, to say the least. All that's changed is how people talk about it. The biology is...interesting...but really not pertinent to this general issue, that IMO nothing new is really being said other than now it's being called an identity and language-oriented normalization issues are arising around it. So that's another ahistorical tacit claim being made.
So I believe you are totally wrong that people previously thought gender was something inborn. Masculin/feminine traits? Yes. But gender was just sex, the thing we call you based on your biology. It was really not complicated.
Gender roles was simply the feminist topic of saying that we don't need to conceptualize women's roles as being fixed based on some tradition or antiquated practice. A woman can wear pants and still be a woman, and in fact still be feminine. That is how gender was used as a word. The only reason it was convenient to call it 'gender roles' rather than 'sex roles' is because the latter makes it sound like it's about the sexual act. But now the word "gender" is being related to one's internal dialogue with oneself, self-image, and other things. Fine, fair enough; but that's just a new usage. We haven't discovered these things newly, just now assigned them to a word that previously did not mean that. It's only a magic trick if you think history started in 2010. The things you mention about whether skirts are only feminine, etc, have
nothing to do with current gender theory vis a vis identity. In fact, you are unwittingly making second-wave feminist arguments here, because the current conception of gender in fact
does presuppose that skirts and dressed
are only feminine, and we know this because someone transitioning M-->F shows it (among other ways) by dressing in a way that's
traditionally feminine.