BlackQuartzSphinx

Lots of great responses here. I just want to add my own reply to your question “why do we need so many terms?”: Specificity.

Any sufficiently matured field, subject, or activity will naturally accumulate more varied and specific terminology so that discussions around it can be more nuanced.

This applies to literally everything, however specifically in the context of identity and sexuality it is very important for people to be able to express themselves and feel like they have been heard and understood.