doesn’t that mean they’re all “not real”?

I don't know. I'd say a "bisexual" is a hetero who likes the occasional homo encounter, or a homo who makes an exception once in a while out of politeness or compassion or curiosity.

Which is to say that I think homosexuality is a more deeply held drive than bisexuality,

Overall, what determines one's sexual preference is a mystery to me, but I am obviously not beyond guessing for the sake of argument.