The material and vibe are great, and hearing the humming on the end of the first track kinda made me wish you'd done more using that since it sounded great!
After listening through all the tracks, i felt you could try playing around with having a bit more rhythm and movement in the backing parts, since for the most part they were just playing the harmony with whole notes, which gets a bit boring after a while.
This could help really elevate the feel of the tracks, because the harmonies and melodies themselves are great.