I has been a while but I've come back with two brand new ideas that are only theory at this moment in time. 1: level wall skip At the beginning of every stage there is a wall blocking you from heading backwards in theory there's no invisible wall meaning that if it were possible to bypass that wall you would activate a level wrap sending you to the end of the level instantly. Unfortunately I can't confirm that it'll work. 2:Walk through wall glitch. Maybe it's possible to simply glitch in walls I will most likely update on this over the coming months.
In the first world there are parts of level with a small amount of Ground in places with wall sometimes you can stand on them and skip parts of the level like when you have to destroy the barrels in the second or third level