Heyo, I see you used Unity 2020 - I also tried to make a web build with 2020 and it had the same issue (I took it down) :| gonna use 2019 next time :)
Woah took me a while to figure out what's going on and that I have to go right and not left :D
Checkpoints - as Amin already said - that definitely is what this needs :D And sound would be cool.