Some people get hung up on the ‘bi’ and protest that gender isn’t binary. In traditional dictionaries:
Homosexual is defined as “attracted to the same sex”
Heterosexual is defined as “attracted to the opposite sex”
So why then dismiss bisexuality as being about “men and women” when the definitions of hetero- and homo- don’t mention those? In this modern age with a wider understanding of gender some would re-state those as:
Homosexual means “attracted to people of broadly the same gender”
Heterosexual means “attracted to people of broadly a different gender”
In fact many people say there’s more than two genders, but if two options are either “the same as me” or “different to me” then we think it’s clear that “both” can refer to those two options rather than two perceived sexes.