Glad you understand. I completely disagree with you in the "terrible" thing. There are many more words that means much worse than terrible. In my dictionary are: atrocious, horrendous, abominable, disgusting, a piece of sh*t, useless... the list keeps going on.
Now, focusing on being productive. I believe you used some body physics 3d / 2d. Although that seems the natural way to go, in most of the cases it is not, specially in platform games where you want to control dash and so on. For something simple like the one you were doing I think something like this could work nicely:
https://kidscancode.org/godot_recipes/3.x/2d/platform_character/index.html
(this guy also have really nice videos about controllers for other things in the game, you should have a look in his youtube channel).
I feel you are more artist than programmer, but you manage to finish the game, so that is a great achievement. Keep working hard and you will succeed.