narcissist traits are just that, traits, it’s a word, a denotation, that might be used to characterize a personality type, not only is it used for clinical type applications, but also has a more common use outside that
narcissist traits probably overlap a bunch of other type things also, which also have names, people are a diverse bunch, the wetware isn’t just from straight unfolded DNA, expressed so, the structures, neural branching isn’t so tight, depends a bunch of factors, gestation through to late teens and beyond, but it’s safe to generalize it’s substantially diverse
i’d be more looking at equilibrium mental states, the backdrop of housekeeping tasks, the internal monologue, and of desires, instrumental desires, depth of orders of intensionality applied to abstracting those in a framework of beliefs, and from that what is impoverished, or washed out, whether it varies or is consistent also
there are structural variations across any population, which has served groups well through history i’d imagine, nature throws broad, of humans, big brain and all that
I might add that environments people are raised can be metaphysically impoverished, which can be developmentally unhelpful