They mean boring

Only the first human was natural, every one after that was created by humans.

…which implies the existence of integer women, real women, complex women, imaginary women, rational & irrational women.

We defied nature so much time ago that calling “natural” any human being that doesn’t live in a tribe in the forest is plain wrong

“Natural” women implies the existence of unnatural, eldritch women, who drive men mad through their ancient Lovecraftian presence.