In practice, it means that each character has a "personality" like "adventurer" or "innocent", and possibly a few personality-related traits like "mindless zombie" or "loner".So so close to something great...
but then they had to ruin it with procedural generation.
Procedural generated characters can't have much personality.
they can have looks. and maybe a trait or two like "tsundere".
but you can't really have proper character development that way.
With sufficiently powerful magical items, it is possible to give a character new personality-related traits. Such as a scary-looking doll making them loners who don't need social interaction. But there is no "character development" in this game, and it isn't actually promised in the description.
Personally, I think this is sufficient level of detalization for this genre. You will find similar levels of "personality" in small settlement sims like Rimworld, which are probably the closest by genre.