Which is appropriate depends on the context in which the sentence occurs.
If you have established a 'Reference Time' (RT) in the 1960s—that is, if before this sentence occurs you are talking about the 1960s, and your discourse will return to the 1960s at some point after this sentence—then the past perfect is called for: it describes the state which obtained in English usage at the start of the period you are talking about.
The need for a gender-neutral 3sg pronoun arose about fifty years ago. "He" as a gender-neutral pronoun had been universally used for centuries before the women's liberation movement in the 1960s; but that movement, &c.
But if you are telling a consecutive story—a narrative in which your RT is continually moving forward in time—then the simple past is called for.
When English personal pronouns settled into their current form in the 13th century, there was no perceived need for a distinct gender-neutral term. He was the 'unmarked' term, and it was taken for granted that it might, in a pinch, serve for either gender. Consequently, "he" was universally used as a gender-neutral pronoun for centuries—until the women's liberation movement in the 1960s. At that time, &c