Going even further back, gender denoted, originally, a linguistical construct associated with sex but not strictly dependent on it, as seen on romance languages like Spanish, Portuguese, etc. [1] There, words have their own gender and, sometimes, the gender of the word and the sex/social gender of the subject may disagree. Ex.: "ant" in Spanish is "hormiga", but this noun is exclusively feminine with no masculine form.

[1] https://etymologyworld.com/item/gender