Thanks for playing and sorry you ended up frustrated! I think I didn't call out enough that you can press R any time to restart from your last checkpoint since that seems to be a common feedback which I took for granted during development. :)
Definitely some more variety in the platforming mechanics and some better communication of the intent and environment would help a lot. It ended up being not at all obvious but the stage of the walking cycle that the creature is in has a pretty significant effect on your momentum, pushing you forward and back as it swings its leg and up and down when it lifts and steps. It was a very intentional inclusion but just didn't end up working that well without more polish.