I'm coming in late on a catch-up but I couldn't resist chiming in:
If it was a book that wasn't strongly about worldbuilding and the world - if it was one of those old-fashioned plots that was primarily about action, about doing things, not people or places or themes - I probably wouldn't notice, and wouldn't care if I did.
If you're going for anything deeper, though - your characters/worlds need some kind of organizing system of belief. It doesn't have to involve gods or afterlives or priests or souls, but (unless you're making them fundamentally cognitively different from humans) there will be some things that the average person takes on faith, that they will use as the foundation for everything else they (think) they know about the world. (Even if those things can be more-or-less objectively proven - like, in our society, 'the earth goes around the sun' - the average member of the society won't have personally done the proof. Unless that fundamental underlying belief is 'taking things on faith is bad and everything must be proven', in which case skepticism then becomes the organizing principle.)
It sounds like when you talk about how the four-species thing works, you've started there - that there are some things about how the four species relate that fundamentally shape your characters' conception of how the world works - and that's the direction I'd go.
The danger of *not* taking the time to figure out what your characters take on faith is that you'll just give them exactly the same principles you have, unexamined, as a default.
no subject
If it was a book that wasn't strongly about worldbuilding and the world - if it was one of those old-fashioned plots that was primarily about action, about doing things, not people or places or themes - I probably wouldn't notice, and wouldn't care if I did.
If you're going for anything deeper, though - your characters/worlds need some kind of organizing system of belief. It doesn't have to involve gods or afterlives or priests or souls, but (unless you're making them fundamentally cognitively different from humans) there will be some things that the average person takes on faith, that they will use as the foundation for everything else they (think) they know about the world. (Even if those things can be more-or-less objectively proven - like, in our society, 'the earth goes around the sun' - the average member of the society won't have personally done the proof. Unless that fundamental underlying belief is 'taking things on faith is bad and everything must be proven', in which case skepticism then becomes the organizing principle.)
It sounds like when you talk about how the four-species thing works, you've started there - that there are some things about how the four species relate that fundamentally shape your characters' conception of how the world works - and that's the direction I'd go.
The danger of *not* taking the time to figure out what your characters take on faith is that you'll just give them exactly the same principles you have, unexamined, as a default.