Lilith's Throne is a game that caters primarily to furries, the human-only option was added as an afterthought to please those who do not like anthros. One of the recurring problems with this game is that it tries to do many things at once and please as many crowds as it can, but being spread so thin means it falls short of everything and fails to please anyone. Most features and mechanics are only half-baked and lack depth, and this is another one of those examples.
As you've realized by now, the options only affect random NPCs by design*1, some of the (non-human) static NPCs have major roles in the story and lore of the world and it wouldn't make much sense for them to humans (humans in this world have the second worst place in the social hierarchy, being only marginally better and more important than imps, which are at bottom). Lilaya, your aunt, is only able to kickstart your adventure because of her predicament, which is attached to her race (and status) as a half-demon.
While some people may argue that the story doesn't matter and gameplay should always come first, this is yet another unfortunate byproduct of a game spread in every direction. When this projected started, Inno intended for it to be an RPG but as time went on more focus was placed on sandbox-y elements... now the community is split on it.
What all of this effectively means however, is that you're strapped for choices if you don't like furries.
*1 (I believe it states somewhere the dev plans to change this further down the line... when, we don't know. I wouldn't hold my breath on it.)
