Instead of doing a tutorial as a separate section, have it part of the gameplay. You could put signs on the wall at the bottom to show what to do initially (movement, jump, and then grapple).
I probably did what many people do and just clicked play, and couldn't get up to the first platform and didn't know about the grapple hook.
You could also make the grapple hook fire by default at 45 degree angles when you press the E or Q keys so that the game doesn't have to incorporate the mouse at all
Viewing post in Crystal Climb jam comments
Firstly thanks for your long and detailed feedback. We are also unhappy with how the tutorial is right now and will change it.
We have some other plans about grappling mechanic and those plans will fix your issues. However this was what we could come up with in 2 days and after rating period we will update it.