Are you an AI?
Certainly reads like one...recently on a zoom meeting the issue of students using AI came up and I pointed out that in English AI has very clear 'voice' and it doesn't take long to recognize it, surely that's the case with Polish too....
certain other species of mammal sex can and does change
Which?
Some fish and amphibians do, but have not heard of a mammal that produces sperm starting to produce eggs instead....
"currently unchangeable"
Gender is a social construct and varies hugely between societies.
Yes, maybe at some point in the future it will be changeable but that is not now.
And yes, gender stereotypes differ a lot between cultures, though again there seem to be limits.... Is there any culture where young women 19-26 are charged with the physical defense of the group and are the first to be sent off to battle? Is there any society where young men of the same age are expected to be the primary caregivers of children?
The default model of original humanity (once a group gets big enough) seems to have a lot more sex-segregation than modern industrial societies... men hang out by themselves and women and children hang out together most of the time.