When you spawn into a level you are slightly above the ground. It you press jump the frame the level loads, or hold jump as you pass this time, you are able to input a jump before you hit the ground. This is displayed in the current Level 30 IL WR to skip the entire thing, https://www.speedrun.com/jelly_escape/runs/y2gv6njz. I am unsure is this has use elsewhere but the run had been bugging me for a long time but now I figured it out.

you can also use this tech in level 51 to save around 7-8 seconds (when done optimally) https://www.speedrun.com/jelly_escape/runs/yo0rj55y