Music is just layered simple patterns and our brains LOVE IT.
Sound is pressure waves, musical notes are a specific pattern of pressure waves. Melodies are repeated musical notes. Songs are repeated melodies following standard structure.
Our brains love trying to decode and parse all these overlapping patterns.
Maybe not really a shower thought and more wild speculation.
Musician here. This is definitely true, BUT interest can also come from subversion of those expectations. Can be seen in prog music and math rock (subversion of musical forms), funk (subversion of rhythmic expectation with lots of upbeats and short notes), etc