Essentially every ancient culture ever to exist possessed some degree of awareness of significant variations in sexuality and gender. Indeed, the evidence in favor of a sophisticated, nuanced view of gender among ancient people is extremely overwhelming based on a huge number of different sources and factors across every continent going back to the earliest written records.
For example, ancient Buddhist texts from the 2nd Century BCE identify both ubhatobyañjanaka (people with both masculine and feminine traits) and paṇḍaka (people with undefinable gender traits which are not meaningfully male or female). Similarly, ancient Sanskrit texts such as the Vedas involve a very complicated lexicon of gender variance. Generally, tritiya-prakrti refers to those people whose gender is vague or undefinable in terms of masculinity or feminity. The term is recognized in a wide array of legal, religious, medical and mythological sources dating as far back as 1500 BCE.
Plato’s Symposium identifies three primordial genders. Male, female, and androgynous. With an additional gender resulting from Zeus’s interventions in human development. The ancient cult of the goddess Cybele utilized priestesses known as gallia who lived as women after engaging in self castration to eliminate any indication of masculinity. While some of these were raised into the cult, many others chose to be initiated and so symbolically change their gender. Keeping in mind, this was only available as a choice to full citizens.
Similar religious orders existed in Akkadian Empire where priestesses known as gala lived entirely as women while also fathering children. These priestess remained highly visible and influential across many Mesopotamian cultures including Babylon, Assyria, and Canaan. Indeed androgynous figures were very common among cultures from this region. In Sumerian mythology, people of no specifically identifiable gender were considered to be divinely created servants of the royal family.
In Japanese religious practices, the Moon kami Tsukiyomi is considered to be androgynous with no definitely identifiable masculine or feminine qualities except in so far as he is referred to by male pronouns and identified as the brother of the Sun kami Amaterasu.
Even Norse religious and mythological tradition recognizes a variety of gender bending figures. Most famously Loki transforms into a woman and gives birth. In some accounts, being raped, but in others seducing and having sex with a male horse. Odin is also repeatedly accused of blurring gender lines by practicing seiðr with heavy suggestions that this exclusively female practice may involve sexual activities of an unmasculine nature.
Honestly, the evidence of ancient awareness of a wide variety of genders is extremely overwhelming and irrefutable. Attempting to deny this awareness is a fools errand with no basis in any meaningful understanding of ancient history.