Thanks for playing! Since this was a jam game I hadn't a lot of time to make tile variations and decorations, so I agree it looks bland at the moment. I do plan to update it, both with some polishing and new content.
There are multiple ways to get up from the second checkpoint: The easy way would be through buying a blue soul from the merchant. You can also exit through the room to the left (with the bats). This room was supposed to be done with a certain upgrade, but it can also be done with a single pink soul and some very tricky platforming.