Biology may not be “destiny,” but biology is important because society has made it important, including making it the main determinant of gender.
These people – these females, these women, with their bodies which could possibly gestate – will always exist, whether we acknowledge the meaning of these bodies or not. And they will suffer, not because of what these bodies do or don’t do, but because of the system which positions owners of these bodies as less human than their male counterparts. The mummy class (many of whom will never become mothers) will be trained up for their subordinate role. Their intellect will be devalued. Their labour will go unrewarded. Their voices will go unheard, or when they are finally raised loud enough, the response will be derision. Men will assume that these bodies and minds exist only to serve their needs. They will assume access to everything: body, mind, identity. To view discrimination against the assumed-to-be-womb-owning class in terms only of workplace discrimination against those who have babies is incredibly short-sighted. What happens to females starts much earlier than that and without feminism, there is no way of avoiding it.
You can’t identify your way out of other people’s perceptions of you based on your sexed body. You cannot, as an individual, create a narrative which transcends “biology is destiny” if your biology has already placed you in the subordinate class (regardless of anything your body actually does). You cannot assume other women, but not you, are deserving of this subordinate status (well, you can. But you shouldn’t). You can talk about gender and identity and your own special sense of self and feel that you are being listened to, but none of this will grant you access to the badge of humanity bestowed on men for something so pitifully insignificant as having a penis. And this is what it comes down to: under patriarchy, ownership of a womb does not mean “someone who will definitely give birth”. It does however mean “someone who is not male and is therefore not quite a person”.