I'm glad you enjoyed the game despite its incredible difficulty. The jump was intended to feel short and unsatisfying to allow for upgrades later in the game to provide a more significant boon. You may have noticed that the controls feel a bit drifty. The reason behind that is to make the game more bouncy and knockback more impactful, though, I definitely overdid it in some areas. Without the drifty air movement, you could just wail on most bosses without them being able to do anything, and I really dislike adding in invulnerability phases. Some of the movement options like the dash and double jump along with the melee attack could have used a bit more polish, so I'll return once the jam is over to refurbish some of the more iffy features and turn this into a full game.
i feel you, handling controls can be a cruel task, i hope you can find the right mix. tho do think about letting the player be as much in control as possible, especially movement. its the first thing you experience in a game it can definitively make or break a game, it HAS to feel good. its the other elements that have to adapt to it, not the other way around. its ok tho if the game is too easy, its a jam game, there’s a bit of “showing off your work” to it, if its too hard it basically become a player filter, and you cant really afford to filter a small playerbase :)
definitively interested by your post jam update, tho dont overscope it, a small completed project is better than an aborted big project :)