The word “sex,” as in whether you are male or female, is not unrelated to the word “sex,” as in getting busy in the bedroom. Sex organs are named for their function–they are used in sex. Sex is the process by which a species reproduces. For humans, sex also may (or may not) be a jolly fun time for its participants, but such entertainment potential does not inform its scientific labeling.
Reproduction in humans is a process that involves exactly two roles and only two roles. Someone provides the gamete called sperm and someone provides the gamete called ova (and in humans, gestates the offspring in a womb). There is not a third gamete.
A given individual can play the male role in reproduction if equipped, the female role if equipped, or neither role if their sex organs are dysfunctional or anomalous. Being “equipped” depends upon normal chromosomal and other development.
Intersex conditions represent a disorder of sex development, not an introduction of new and additional kinds of sex development. They don’t provide a third gamete or perform a third role, much less a “spectrum” of gametes or roles.
The idea that sex is a spectrum comes from the view that a person’s sex is primarily interesting or erotic or an impetus for self-expression, and overlooks its function. It’s an ideological concept, not a scientific one.