Historically the harmony was created at the 2nd generation of music (classical polyphonic music) as a drone simple countermelody of rather complicated melodies So there is the pre-occupation that melodies are complicated and accompanying harmonies are simple. And indeed there is a large number of famous folk and artistic songs that it is so.
Nevertheless after the 3rd and 4th generations of music (Jazz, folk jazz and digital music) we notice the reversing of this and we have a large number of beatiful songs where the melody is very simple while the parallele chord progression is complicated. Sometimes there is a larger number of chords compared to notes in the melody, or we have a single note in the melody having two accomanying chords etc. Here the harmony of the accompanying chord progression is like a polyphonic countermelody which is more complicated than the melody itself.
A classical example the famous Lous Armstrong song What a wonderful world
https://www.youtube.com/watch?v=uBs82KnJllgIn the 4th generation of music , the digital music with looping and arpeggiators , this mode of songs with simple melody and complicated harmony is more often and also easier to compose, when you are a (jazz) guitarist who has spent much time in learning and feeling chord progressions.
