1- I still don't see why wouldn't you invert every level to have the gravity normal.
2- I mean your vertical movement seems very much like in Flappy Bird: each button press sends you "up" by a fixed specific amount (of speed). I thought the movement is the same in horizontal, but after trying the "guides" you mention, I can see that I was wrong. There is nothing wrong with the movement.
There is a problem with the difficulty curve. Your "guides" are actually tutorials. So I would suggest to put them as ordinary levels just before the level where the corresponding mechanics occurs for the first time. Otherwise, nobody is going to find them. Also maybe have much less difficult (or much shorter) levels at first; I think you start too hard.