Thank you for your feedback.
The jump you mentioned should not be impossible as you can hold shift to sprint and you can double jump. You may be jumping to the wrong platform? And if the case, that is indeed on me. I agree that you should have a clue on where to go.
There is no point to flipping but to have fun. It was purposely made to be optional, since some people may not like it. I've seen a few comments so far with a dislike towards the camera flip, so if I were to redo the game I may remove it overall.
The instructions of the game are more learning-based, kind of like the original Super Mario bros. In the game you don't know much. But you learn through playing that you can sprint, get coins from blocks, and reach a flagpole that takes you to another level. This approach was applied in my game as the player is supposed to learn the timing of the jumps, that the power ups let you progress, and the portal at the end of each level takes you to the next.