Just ask yourself, wouldn't it be a shame if there was no one around to listen to Beethoven or Mozart, to look at Monet or Van Gogh Paintings, or to appreciate the sound of poetry or the movement of a dancer? I think denying that humans are social beings in a massive social network is easy, that way nothing we do really "matters" to the universe, even though it matters intensely to other humans.
I notice the specific examples you list here are part of the western canon, which I assume is part of your culture and therefore important to you. But you didn’t list any artists from other cultures. Why do you think people living in another planet some time in the distant future would miss the artists from your culture? Wouldn’t they have their own art and music unique to them that they would care about more than the things you care about?
I get that it’s sad to think about these artists dying for good (as in their art being wiped from collective memory) but it’s something that happens all the time to artists throughout history, and I really don’t think it’s a great shame on a cosmic scale that the artists you mention might be forgotten in the future. I think as much as you would want to share Mozart with the Martians, they will care about him just as much as you care about artists from South America in the year 900. That is to say, not at all.