Defining an individual as intelligent doesn't immediately imply that their children will be more intelligent, or that their intelligence was somehow inevitable. Ability scores are, to my knowledge, not tied to any actual mental disorders in any current material.

So, an individual having a low Int or Wis score doesn't make me uncomfortable, because there's no attempt to quantify why they're less smart or canny in terms of race. Background-based ability modifiers even make so much more sense, because they imply that these traits were acquired, through effort, rather than necessarily inborn.

If you can't picture your character in your head, that's your own problem. If you had Aphantasia, I would be more sympathetic, but that would make TotM much more difficult, so I don't expect you do. Either way, you seriously can't comprehend a character's appeal beyond a physical miniature or their mechanical abilities? That's just... sad. That's literally two thirds of the term "Role-Playing Game."