This is a cool game!
For the jet pack, I actually didn't have too much trouble as other people did once I got used to it. But I think having it accessible without having to jump (pressing up on the ground lifts you in the air while activating the jet pack) or just pressing jump twice to activate it might make it easier for others.
For the jump itself, I think adding a bit of hang time while she's in the air would make it feel a lot better. right now it seems really award since she starts to fall immediately after she stops rising. The height doesn't need to change, but adding a bit of a delay before she starts falling would make jumping feel a lot better.
Also, I think when you go back too the ship, it should put you in the warp pod or whatever it is that the player warps from. As it is now, you always have to go back to the room with the warp pod in it even when you just make a mistake on which planet you want to go to so it can get a bit annoying after a while.
Great job on everything so far, keep it up! :D