If you look at some of the most innovative places in history, they weren't particularly diverse. It doesn't seem to have held them back. Renaissance Florence wasn't especially diverse, it was a bunch of Florentines sitting around doing Florentine things. Victorian London wasn't all that diverse, either, but they were innovating at an astounding rate.
Bell Labs in the 1960s was mostly nerdy white dudes with pocket protectors, and they were massively innovative -- because what drives innovation is thoughts like "What if we laid down amorphous silicon dioxide directly onto the wafer and annealed it to reduce electron traps?" rather than thoughts like "omg, I just saw a person with a different colour skin, my mind is totally blown".