You could also interpret any possible plurality as Adam being a representation of mankind, as some Christians do.
In your studies when people are translating the Hebrew word to "Them" is it because it's a non gendered singular pronoun, or that it's a collective pronoun? (I'm not certain they are the same thing in Hebrew as they are in English).
He seems unambiguously male in modern English Christian versions, but apparently it's less clear in context of original translations.
Some Jewish folklore has Adam and Lilith being created as one creature who were then split in two. But Lilith was rebellious and didn't want to be a wife, so God banished her and crafted Eve from Adam's rib.