I wouldn’t say that any specific skill (like literacy) is required to have intelligence. It’s more the capability to learn skills and build a model of the world and the people in it using abstract reasoning.
Otherwise we would have to say that pre-literacy societies lacked intelligence, which would be silly since they are the ones that invented writing in the first place!
Otherwise we would have to say that pre-literacy societies lacked intelligence, which would be silly since they are the ones that invented writing in the first place!