What you're saying isn't really proof that same sex desire exists in everyone. Like I believe that there are probably more bisexuals(the kinsey .9s and the 5.9s) than we think, but that doesn't mean that everyone is bi or has the potential for same or opposite sex desire. So in the times of Sparta etc, it might have been more accepted for those already bi people to express their bisexuality. And I'm not even talking scientifically here, I'm just talking about what people say about the subject. There's some research and some ignorant people who seem to believe that all women are bi or "don't have a sexuality" as I saw one guy say, but I've met women who were 100% straight. One girl wouldn't even kiss another girl for 200$ because the thought disgusted her so much. "Ugh, it would be like kissing my mom, no offense" was what she said to the proposal. Most men report no sexual attraction to other men. I mean, I think its kind of rude to respond to a person telling you "I'm not attracted to these people" with, "you could be/you are its just society saying otherwise". Its remarkably close to TRA arguments.

Also, NO opposite sex desire is NOT grounded in male domination or female slavery. Straight people's sexual desire is for the opposite sex regardless of how they feel about sex stereotypes. Many straight women don't like being dominated sexually and prefer sex to be more equal between partners yet they are still straight. They go and find men willing to accommodate them, they don't go to having sex with women. And the rare cases of submissive straight dudes I've seen would rather stay celibate than fuck another man.