Identical? Is every single biologically born woman identical to one another? We are obviously very different to each other, we are not identical.
No, we are not identical. Apart from being born human and female, there is not one experience that all female humans have in common. However, there are experiences that only women and girls qua females can have.
The male human does not menstruate or ovulate, does not have medical investigations if he doesn't do either, worry about getting pregnant from rape, need an abortion, has breasts ironed flat or labia and clitoris cut off to keep him pure, is not forced into marriage aged 12, is not fired for being pregnant or demoted after giving birth.
No male human knows what it feels like when a nine-month-fetus seems to want to box its way out of the womb that shelters it or when another human being can survive entirely on the food his body produces.
(Not an exhaustive list)
While not all women qua adult human females share these or any of the other exclusively female experiences, enough of us share some of these experiences to make womanhood a collective experience, especially as lived by the females of one region, culture and time period.
For instance, 96 to 97% of women menstruate, 80% of UK women become mothers, 70% experience sexual harassment, 40% male sexual or physical violence and - as an example for the unpaid labour burdens that continue fall disproportionately on females - UK women aged 45 to 54 women are four times as likely as men to reduce working hours to care for a loved one. And so on.
Many of us share some, many or most of these and other exclusively female experiences.
Womanhood - the sum of our experiences as females in a male-dominated world - is the state of being a woman. A state which is based on having any number of exclusively female experiences, in common with billions of other women throughout the past and present. It is therefore something that only women qua females can experience.
Men, including those claiming womanhood, can of course share some of our experiences that are not rooted in female biology but that are nonetheless more typically encountered by the female of the species. That doesn't make them women or their experience womanhood.