Level designer here. Actually the cube is not required to make that particular jump. The player can make both of those gaps with a well timed sprint jump.
It would be extremely difficult to get a cube up there with you to make that jump, if not impossible. I would be impressed if you did lol.
I think we need to tweak player movement a bit. It's unexpected that the player can make such a gap without a cube. Also including a prompt for the player to hold shift since this is one of the first large gaps could help.
Thanks for playing and the valuable feedback :)