Human civilization is a lot longer than history and a lot more complex than specific normative behaviors blipping into existence at some defined point in time. Check out The Dawn of Everything for a recent anthropological perspective.

Various cultures approach gender and sex (and thus sexuality) differently. Homophobia as we understand it can’t exist universally because sexuality as a static individual trait isn’t a universal conception. Though that doesn’t mean there aren’t other norms and deviations and whatnot.

Caliban and the Witch is adjacent to this topic and discusses how sex and gender norms developed out of middle age Europe.