It doesn't belong to the "old ones", it is at best a derivative work. And even writing a prompt, as trivial as it might seem, makes you an artist. There are modern artists exposing a random shit as art, and you may or may not like it, but they are legally artists, and it is their work.

The question is about fair use. That is, are you allowed to use pictures in the dataset without permission. It is a tricky question. On one extreme, you won't be able to do anything withing infringing some kind of copyright. Used the same color as I did? I will sue you. On the other extreme, you essentially abolish intellectual property. Copying another artist style in your own work is usually fair use, and that's essentially what generative AI do, so I guess that's how it will go, but it will most likely depends on how judges and legislators see the thing, and different countries probably will have different ideas.