Don’t be scared of music theory ir is way simpler than languages and having even a little basic knowledge really opens a lot of doors. I often think a lot of people like to male is seem more complicated that it need be to make themselves sound/feel important or superior. Remember There are only 12 notes so it can’t be that hard. Don’t try and master everything in one go either. Start by learning as much as you can about the basic major scale and the chords that can be built from it. You will be amazed at how much you can do with nothing more than a deep knowledge of the major scale.
Good luck and remember to report back and let us know how you get on experimenting with the harmoniser.