Your playing doesn't "matter" in the way Bach's original composition "matters." One of these things has been remembered for hundreds of years, and one of these things would never have been remembered unless you reinterpreted the work in some novel way that reached millions of people.

The fact that Bach's compositions can be encoded as a number doesn't mean that it wouldn't take a genius of Bach's level to deserialize that particular number, which could literally be deserialized into a representation of any arbitrary thing in existence with the correct algorithm, any less novel when it was created. The same holds true of your comment. Just because I declare 1001 represents a beautifully unique masterpiece, once it is decoded, does not make that masterpiece actually exist.

Bach was important. In a world with general AI no human will have the ability to be important in that way ever again. At first AI will create crude imitations of human art. Then it will create hundreds of billions of creative works that are more human than human. Then it will create artworks that surpass our ability to comprehend. I don't know about you, but the inability to do anything novel as a species, to learn anything new, is a terribly bleak possibility.