Humans are not "man
XOR
woman".
Humans "differ individually between models of masculinity, femininity, and atypicality, on a range of biological structures". When that is simplified to "man or woman" without the "XOR" it is a discussion of some field of those factors.
People either exclusively do, or exclusively do not get exposed to testosterone over the previous six months of some notable level. We can quantify normal ranges and averages, but nobody is exactly the average unless they manage towards a whole population mode, and this is just one factor!
There is also estrogen, which varies the same way. Already the two primary signals that trigger SOME major differentiations are on an identifiable spectrum
There are other signals and receptors for gender, many of which are cultural.
People do not produce exclusively sperms or eggs. Some produce both. Some produce neither. Only "most" one XOR the other.
People do not have one exclusive brain structure or another one. It is not a dichotomy. It is an option between many, for many structures, both in the brain and in the body.
The problem with this is that we evolved as people who have to be wrong before we become right, who are born in ignorance of all this, and who often lack of outright ability to process something as complicated as gender. Without education, hard work to discover things worth educating about, and people capable of actually doing that work, we end up with people who actually believe sex is an XOR.