These pagan cultures probably came to the conclusion if they wanted their people to survive, have children and continue their lineage, heterosexual acts provided a higher level of success in attaining that goal than homosexual acts did. Of course by my stating what used to be known as common sense I am now guilty of “hate speech.”
Regardless if they were pagan of not, and most primitive tribes had pagan religions of some type, almost all tribes had taboos against homosexuality. Heterosexuality brings stability to a tribe, can't have families without hetero behavior. The communist know this and one of the first things they do, and our country is a prime example of it, is to dismantle the taboos on homosexuality. This throws the country, or tribe as in the case of African areas they have worked this on, think Mau-Mau, into instability, does away with morals and guidelines and replaces it with the government as the new religion.
Make no mistake, there is the reason queers are being pushed onto America and it is working so far.