I ended up finding 4 ( + 1) new strats while experimenting with this game.

Strat 1 (Billy's return!)

You'll see Billy near the entrance of the room that you unlock after the target puzzle

When you walk on Billy it after you knocked them down, Billy has a chance to launch you into the air sadly the launching isn't consistent. Do multiple attempts to get launched by Billy until you get inside.

After you get the orange key you can find a grayish brown trapezoid, you can jump onto the trapezoid to leave the area.

2nd Strat

There are 2 boxes at the end of snake area, when you start the puzzle push one of the boxes towards the parkour area

Most likely you wont have enough time to make the box touch the wall, so push it as far as you can. After the puzzle ended push the box until its connected to the wall and then pick up the key, and go to the parkour area via the box

Minor Skip

After you get the red key jump in the direction of the boxes

3rd Strat

During the maze there is a jump scare move to the right of the bear and grab the key.

4th Strat

After you pick up the pink key on your way out when you see this, go towards the same direction as the arrow

and you'll see a box that you can push towards the fence and jump over it

(Slow for example)