They're saying that creativity isn't in a vacuum. Both Bach and Shakespeare were both inspired, and drew upon many things in their life. Just like how anyone who makes anything or does anything leans at least a little on past experiences. And I really think that line of arugment is a dead end, and only hurts, or we'd have to round up and arrest every highschooler making shitty anime fan art.

You're reaching pretty far back to find outstanding examples, and I'll agree they are way above average.

However, I'll assume you know that most of Shakespeare's works were based off of earlier works. And I doubt Back taught himself from scratch either.

Not just based off, but in some cases blatant ripoffs. Shakespeare was famous for swiping the plots of Italian plays. Ever notice how many of his plays are set in Italy? This was before "remix" was a word.

Shakespeare's specialty was writing clever dialog (and to give credit where it's due, he was very, very good at that), not coming up with totally original plays.

If copyright as we know it had existed in Shakespeare's time, he would have been sued into a smoking crater.

Neither Bach nor Shakespeare had copyright over their works, as the very concept of copyright didn't exist until the Statute of Anne in 1710. Germany (really, Saxony, as Germany wasn't even a unified country at the time) was much later.

Shakespeare got paid by people buying tickets to the Globe Theatre, of which he was part owner. Bach got paid by various princes and the church, and was expected to compose new music every week in return for his pay.

Neither argued that they should continue to get paid for the same work for 90 years.