You don’t define the norm with characteristics of edge cases

Good thing I didn’t do that.

The X and Y chromosome groups define biological sex

This is the whole point, no, they don’t. Biologists do not define sex in terms of chromosomes because there are multiple different chromosomal systems in use to achieve the function of sex cell differentiation.

Some people are born with vestigial tails, does that mean that humans may or may not have tails? No, a few hundred people have been born with a vestigial tail in recorded history.

Some people are born with a cleft pallette, does that mean humans can be born with or without a cleft pallette? No, 1 in 1,600 people are born with a cleft pallette.

I just…fucking wow. Reread what you wrote here.