How to choose a chord progression for a melody in a very simple manner
There is only so much creativity you can expect from a computer. Adding chords to a melody is something that needs a human touch. It is not that hard. First learn to play the melody in the key of C. That is start the first note higher or lower until you can play the entire melody with only the white keys. You can always set the transposition to get back the original melody. Now while playing the melody with the right hand, try 3-finger chords with the left hand. In the key of C there are only 6 different chords that are basicly needed: C, F, G, Dm, Em and Am. Each of this chords consists of the key that it is named after and two higher white keys with one unused white key in beween each of them. You will find the right chords matching the melody in a short time. Now make an arrangement in One Man Band.