So let's look at the words we use in English for various animals. Female first, then male.
Pig - sow, boar
Whale, dolphin, porpoise - cow, bull
Rabbits, hares - jill, jack
Antelope, deer - doe, buck
Goat - nanny, billy
And so on.
We do this for humans too. Woman, man for the adults. Girl, boy for the juveniles.
Why do we have different words for the female and male of the species? Because it matters to know which is which. Reproduction is absolutely fundamental for every species of life. The species that use sexual reproduction rather than asexual (cloning) would be up a gumtree if members of the species couldn't recognise which sex other members are.
This doesn't mean that humans who don't reproduce through choice or circumstances or medical problems are not human or not valid females/males. But anybody who thinks their sex is something they can conceal or which won't make a difference to how they're perceived and treated is living in a dream world.
And now gender ideologues are telling us that the words woman, man, boy, girl and all the other words that relate to biological sex in humans should be redefined on their say so to relate to gender identity, a concept so nebulous that it's impossible to define.
People who accept this leave us with no words that mean female human or male human. This matters. Sexism is not based on gender identity, it's based on which sex a human is perceived to be. Same-sex attracted people aren't discriminated against because they are attracted to people of the same gender.
Thank goodness for JKR. 