Define what characteristics are reqired to be a woman. You can't just say a horse is a horse without being able to define what characteristics are required for it to be a horse.
And that is all the anti-trans people have doe so far, persistently stated that a woman is a woman without defining the required characteristics to be a woman.
Men, women and intersex are built differently. The anti-trans brigade are having great difficulty in explaining how they are built differently.
The pro-trans brigade put it very simply: Sex is not binary, it's a spectrum. Agreed the vast majority can be accommodated into one or the other category, but billions of others don't and haven't. You cannot just deny their existence nor their human rights