Lots of common people did listen to Bach, because he wrote many works for church organ. Church attendance was almost universal, and even small churches had (small) pipe organs.
His work was not commonly performed in his lifetime, and I think you're rather proving my own point? Yes, they could perhaps occasionally listen to Bach, if the organist at their church was aware of him (most would not have been, not until hundreds of years later), had the music, were willing to perform it, and you happened to be in attendance when they did. That's a lot of chained ands.
