I've sort of developed a strange relationship with the concept of "realism" in the things I make.
Something I was very into as like, an eleven year old (im not implying this was immature to be into, just that it was formative for me), was speculative biology specifically for dragons, and now, specifically in the case of dragons I find a lot of attempts to make them biologically plausible fully missing the appeal of dragons at all.
Thinking specifically about the supernatural elements of JoM and where the line is drawn. The dagnyds are made from the remains of godlike entities, and are not entirely earthly animals. They have a supernatural origin. It would be fully justified in giving them magic abilities or making magic an aspect of the setting, but have absolutely zero interest in doing so. It doesn't interest me. I think about shit like healing powers or glowy energy attacks and my reaction is just "what does this even add? Why do I need this? Does this make things more interesting?" And it simply doesn't. Healing is more interesting as a prolonged process, combat is more interesting with teeth and claws and metal and blood. These are options which are more realistic, closer to real life, but the realism isn't what makes them interesting: it's physicality.
When I design a creature for this world, I am not thinking about making it biologically plausible, and yet, I try to design things which look like they could 'move under their own power'. There is a sense of heft and mechanical "soundness" which I value more than realism, but often also aligns with looking 'realistic'.
I would say that it's better to serve a narrative than strive for absolute realism, but I don't actually write stories, although I do have ideas for them occasionally. I guess a version of this which is more relevant and applicable is that i prefer to strive for a particular vibe.