I think there's a range of frequencies/vibrations of sound that our brains naturally enjoy. We know right away whether it sounds good or bad to us, the same way that we do with how food tastes. We can develop our taste and understanding of music, but we'll always have a starting palate of sound preferences.

"More complex and interesting" is subjective. Pop music is music that appeals, sonically and thematically, to the broadest spectrum of listeners. That requires its own genius to achieve.

When I'm trying to find new music on Spotify I click 10-15 seconds into a song, listen for a couple seconds, and then skip to the halfway point and listen for a couple seconds. I can usually tell from that whether I'll like a song. Some songs stand out to me as bad on first listen. A lot of those I will add to my liked songs and listen to again later. I often end up enjoying those. It's the songs that provoke no reaction in me that I can safely ignore.