Auxlian: An umbrella term for being something that appears as or imitates humanity/humans, but in reality isn't human. In other words, a form of nonhumanity that appears like or imitates humanity on the surface. (Prefixes: Aux-, Auxli-)
Examples of this include, but are not limited to: Shadow people, humanoid beings/monsters/etc., some shapeshifters and polymorphs, mimics, uncanny beings that look less human the closer you get, and many others.
Auxlian can describe gender, alterhumanity, aldernicism, and many other categories, depending on what you put at the end of the prefix (aux-, auxli-). For instance, the terms below. Furthermore, these terms may have subsets themselves, as auxlian is an umbrella term.
Auxgender/Auxligender: An auxlian gender. A gender that imitates/appears as human(ity), but is not human.
Auxbeing/Auxlibeing: An auxlian alterhuman identity that imitates/appears as human(ity), but is not human. Can also be called auxhuman or auxlihuman.
Auxdernic/Auxlidernic: An auxlian aldernic identity. A form of aldernic that imitates/appears as human(ity), but is not human.
Because of how many wide ranges of experiences can be under this term, feel free to make your own subsets, especially for gender identities and such. If auxlian genders need an in-nature term in the future, it can be called AUXIN.
Comes from the term "aux," which is synonymous to alternate. "Aux" may be pronounced like "ox," or it can be pronounced like "oh" (French pronunciation.)