Okay, I tried this again today and had 10 straight minutes of every single attempt bugging out in various ways, so I'm simply done with this. On the off chance it is helpful I took a few screenshots of what is going wrong.
Here is me falling short of this jump one of several times despite just holding down D or right on the stick the whole time (I alternated to see if it made a difference). As you can see I am currently midway through the pinkish purple hand that in theory should kill me, I will continue to fall off the bottom of the screen as the background scrolls downwards until it no longer can scroll any further. The only way out is to go back to the start menu via pause.
Here is a slightly different version of the second bug I mentioned before. I fell down here and got stuck in the floor unable to move rather than fall all the way through and then falling forever. I figured I would wait for the pursuing hands to kill me but as you can see they just passed right on by the little girl and her blue orb. I eventually tried to kill myself by maneuvering the blue orb directly into one of those shadow people which A) did not kill me, and B) somehow caused the girl to finally fall through the floor and drop endlessly.
I reset again, fell on those opening jumps a couple more times (each time resulting in an endless fall) and gave up. FWIW the game up until this point wasn't really buggy at all, there was one time (the part with the pipes you can walk through if you want) where I sorta fell/clipped a bit into the top of a pipe and got stuck but that's about it.
EDIT: Had an idea today, redownloaded the game and checked if that would maybe fix things.
It did not, but I learned that the collision detection on the hands just ain't working at all as this was from me not moving from the start of this section. At this point I am out of ideas, either a recent-ish update to the game borked this section or my game save is causing this somehow as, again, I moved its entire game install folder to the desktop as a "just in case" backup, redownloaded from itch, extracted to a new install folder and it is still like this.