Thanks for your very valuable feedback !
I agree with most of your points, level design is not my strong suit, especially in a jam where time is limited, but I'll keep working on it ! What happened is that I made something quite linear, but noticed it was possible to get softlock, so I added things to prevent that, which worked but allowed the player to do things in a different order, and might make the player feel a bit lost. I learned a lot during this jam, I'm sure I'll do better next time !
Unline the original Snake game, you don't die when you touch your tail, but when you get stuck and stop moving for a while. That is why the death animation felt long, you still can escape if you manage to move. I will remove the forced death, it was here to explain the death mechanic, but I agree it was done poorly. I'm still trying to find a better way to explain that without using too much text.