Intelligence in a game like D&D has only a tenuous relationship with IQ. One thing to realize is that stats in the game, in the end, tell you only how stats behave in the game. If you wanted to give the Scooby-Doo gang stats in a D&D-like game, they would all have massive Intelligence and Wisdom scores... not because they are all stated to be super-geniuses, but because they routinely succeed at tasks of intelligence that other characters in the show fail. Similarly, Peter Parker must have a higher Intelligence than most scientists, at least on a Leonardo da Vinci level, because he routinely succeeds at scientific and engineering achievements that are beyond what a normal "genius" can accomplish. Think about all the "intelligent" characters in shows who are stated to be intelligent just so they can be proven wrong.
All a low or high Intelligence really means in D&D is "knows more languages" or "knows less languages," "is better or worse at Intelligence skills or proficiencies," and "does or does not often succeed at Intelligence checks." Role-playing them as some stereotype of a given IQ isn't required. The game already defines what the game defines. The only ability scores with really tangible meaning are Strength, which allows you to lift or carry a specific amount of weight, and Constitution, which is sometimes used to measure how long you can hold your breath or how many hours you can march. Other than that, the scores are just "how often this character attempts and succeeds at tasks of this nature." Your dashing and handsome and dashing swashbuckler only has Charisma 7? They are just the unfortunate victim of comedy writing.
