I've said this 2-3 times already but maybe because it's a field I'm steeped in it makes sense to me in a way that hasn't clicked for you (yet). Gender roles seem to have arisen in order to ensure that all the work gets done - and at the same time many if not most forager cultures don't really pay that much attention to them (even though they exist). Autonomy is a much more deeply held value than performance of gender - up until the rise of patriarchy about 6-8k years ago. Hunter-gatherers trying to keep their band alive didn't really have the luxury of caring too much about who does what. If a woman is a good hunter, she hunts. If a man likes to care for children, he does that. Strict gender roles are irrelevant in an egalitarian forager culture where intense individualism is employed to be of use to the greater group.

And, as already noted several times as well, the fact that gender roles and norms are often quite different from culture to culture, often diametrically opposed to those of other cultures, speaks to their artificiality.

You seem to have a little flavor of evolutionary psychology going on here, but I’m working on a story now about just how much junk science that shit is. It’s essentially patriarchy trying to justify itself by pretending it’s “science” when it’s really just unsupported conjecture.

Suddenly, with patriarchy, there are no longer 3 or 5 genders where people contribute to the group in whatever ways they choose, there are now only 2 and one gets to hold all the power while the other one becomes a sort of social child, controlled first by her father, and then by her husband. This gets strictly enforced from then on because patriarchy is a way of grabbing power and maintaining it through laws, customs, and violence if necessary. The Kurgans (and probably the early Hebrews invaders as well) would sweep into an egalitarian village or settlement and kill all the men and children, taking the women as "war brides" to become the mothers of their offspring. Just because the legacy of that is ubiquitous in Western (and some Eastern) history for the past few thousand years doesn't mean it's always been that way or that it's universal even now.