I don't know much music theory but the chord progression in the first 4 bars it seems to deliberately miss the final chord, which leaves us without resolution.

I don't know much music theory but the chord progression in the first 4 bars it seems to deliberately miss the final chord, which leaves us without resolution. The next chord sounds like a change but we don't know what the root it is going to (so any chord would make sense, may it be a minor 6th or 3rd). Then there's this pedal note that is through the whole tune. It can be a tonic or a 7th so very ambiguous. It reminds me of some musicians that try to comp songs that they don't know (neither the theme melody or chords). Play this way they can easily add one or two notes from the keyboard to a big 7 major/minor/dominant chord and seem to follow the song's chord progression, while the singer will add colour and melody. The audience's brain will fill the gap by themselves.