I wouldn’t consider someone who didn’t do the painting themselves to be the artist of a painting either. You could call them the art director or something, but they are at most a coauthor of the art. They are not making all of the artistic decisions. That’s pretty similar to AI art.

Found objects have about the same artistic value as well-made AI art too, yeah. You’re going through a selection process to find something that appears pleasing. I think AI art is more similar to directing, but found art isn’t far off.