What might aliens make of the way music affects us? Or poetry? Or art?
Many species on our planet make music, so they’d probably understand it as a property of complex life on Earth, not merely of humanity.
But I wonder whether they’d have an emotional reaction to it? I believe any complex intelligence would require emotions, and, as birdsong illustrates, that music is emotion communication, so the idea isn’t as daft as it might initially seem. The difficulty is the aliens: to understand their prospective emotional reaction to our art, if any, we’d have to understand their experience of emotion, their concept of beauty, and their concept of art.
It’s reasonably clear aliens don’t exist, at least not for us, not in this part of the universe at the moment (indeed, possibly not in the universe at all). The only way we could answer the question is by inventing some aliens to ask. The problem with that, of course, is that our inventions would be reflections of ourselves. This means the only answer to the question that we can give right now would be found by looking inside ourselves.
In other words, the correct answer to the question of ‘what might aliens make of our art?’ is ‘whatever you want them to’. Really, it’s an unanswerable question.