Too bad your jam version had the bug for changing levels. I played both version (for the jam, and the fixed one). The portal bug where you can't finish the level is fixed, so that is good. Be careful on your fixed version, it seems the "return to menu" button is doing a restart of level instead
The low poly art is sweet, the little rocks flying is cool... nice world.
For the bugs: when trying to change player after one pass through a portal is making the game freeze.
I think the sfx for the jump is too loud. Also the sfx for dying is played when you walk out of a button it seems. Lastly, for sfx, we can hear footsteps when jumping ;)
Also, I felt like jumping was a bit strange, maybe changing the velocity (like if you walk you can go quicker than when you jump) would make things feel better?
Finally, I really like the menu, being the first level in background. But you can see one flying text, it should not appear in the menu imo
Overall a nice start ;) Think about adding a story to make us want to go on the goal, and play more levels.