This a very silly view of the past through modern eyes. Intelligence, cunning, and wit have always been immensely valuable. Read the mythology of literally any culture for examples.

To extrapolate from fewer people were formally educated or literate to intelligence wasn’t valued is absurd.

As for your part about reading and writing. Literacy has always been a very valuable skill that would increase your social standing. It was scarce and difficult to acquire before the printing press, but it was always valuable.