> You should give this page a read: https://en.wikipedia.org/wiki/Gender

The very first sentence of that Wikipedia article (let alone the rest of it) corroborates my comment.

> The concept you are referring to is "sex".

No, the concept I am referring to is gender. Sex is a spectrum, too, but that doesn't mean that gender is not.

Sex is not a spectrum, there's no ranges of intermediate sexes between female and male that produce some other types of gamete.

Sex encompasses more than the production of some gamete; it includes genetic and anatomical determinants, and it ain't exactly unheard of for those to get out of sync or otherwise produce sexes that are neither unambiguously male nor unambiguously female.