You certainly have some interesting mechanics, but maybe they're too many and not well explained. If there's friction even trying to climb a rope, there's a problem. I think most of it would be solved with a less minimal UI that showed what every button action currently is, what amount of items you have and how much the bag is slowing you down.
I found throwing mid jump then catching the bag in a lighter jump a fun gameplay experience, trying to aim well so you don't lose your progress. I think adding to that tand dialing back on how limited the rest of the items are would make a more satisfactory game.
I also found some background elements hard to grasp if they blocked the way or not, it didn't seem too consistent. I think adding more colors would help. I know the GB is limited, but this reads more as 2 bit than 8.
Congrats on making something this deep mechanically on time!