Hi! Thank you so much for your post! Glad that you enjoyed our game that much, it does mean a lot.
Yes, the frog is jumping inside the snake and the idea is that because the snake is also eating itself (like the ouroboros snake), then you repeat the levels.
To wall-jump you have to buy the upgrade that costs 15 golden flies at the shop. With these upgrades you'll be able to collect the insects.
Again, thanks for taking your time to leave such a great feedback, we are totally aware of the problems with the game and we are excited to fix them after the game jam finishes.