In your painting example though, surely the end result would be far too obviously transformative to ever be in any danger of accusations of copyright infringeme

In your painting example though, surely the end result would be far too obviously transformative to ever be in any danger of accusations of copyright infringement, copying, piracy, stealing, or any of that? I mean look at Madeon’s Pop Culture song - wouldn’t “stealing tiny bits of other people’s work; reassembling it and calling it something new” describe it pretty completely? Except that track is a masterwork in the mashup genre. The bits aren’t ‘stolen’ they’re just ‘used’ and the entire concept of the song revolves around them being immediately recognizable.