Folks who at various times in their lives display gynesexual characteristics and at other times display androsexual characteristics are amphisexuals — or simply human, if you prefer a shorter word. Human sexuality is a fluid continuum, not a Boolean characteristic.
Particularly when used as noun rather than as adjectively, words like homosexual and heterosexual carry heavy connotations of morality, exclusivity, culture, identity, and expression. They work better to describe relationships or acts than they do to describe people. Used to describe people, these terms can easily come off sounding judgemental, and are seldom 100% accurate in all regards anyway.
Someone who is sexually attracted to one gender may or may not be sexually attracted to the other gender, and they may or may not be sexually repulsed
by the other gender. They may form romantic attachments with only one gender yet engage in sexual behavior with both. Finally, all this is much more fluid than the clinical-sounding terms may suggest, as even within the same individual it can vary significantly with time and circumstance.
For example, I have personally known both men and women who identify as “straight”, yet who sometimes engage in non-romantic sexual activity with members of their same sex. Clearly, they are not repulsed by their own sex, yet at the same time they do not consider themselves “bisexual”. Indeed, they reject that term if applied to them, probably because of the social connotations, and perhaps because they do not form romantic relationships with their own sex.
This actually works the other direction, too. I’ve also known both men and women who, despite self-identifying as “gay”, have been known to have sexual (but not romantic) relations with members of the opposite sex. These folks might be somewhat less likely to reject the “bisexual” label with quite the same vehemence as the corresponding self-identifying “straight” people often are. But they still think it a mere technicality, and so do not change their constructed cultural identification just because of some occasional dalliance outside of that consensus construct.
I’m reminded of this bit of dialogue from the musical Hair:
Prison Psychiatrist: And men?
Woof: What do you mean...?
Prison Psychiatrist: You have any sexual attraction towards men?
Woof: You mean if I'm a homosexual or something like that?
Prison Psychiatrist: Yeah.
Woof: Well, I wouldn't kick Mick Jagger out of my bed, but uh, I'm not a homosexual, no.
Probably that could stand some updating for today’s audiences, swapping in someone younger for Mick Jagger, but the expressed sentiment is ageless.