Thank you for the comment! Well, when you only have a month to do coding, planning, designing, spriting and a bunch of other stuff I wasn't able to really make as many assets as I'd like. I was even still late because of it. I was supposed to have like, 4 areas for this game jam, but I overestimated my abilities to do so. Hence why places are locked off. I'll try and figure out a nice mix of gameplay with the blocks. By the time I got a reply from another friend it was too late to change much.
As for the powers, powers will never affect if you can progress through the game or not. Think Charms from Hollowknight. An additional thing that can help you, but won't strand you if you get it. Any powers you do get that affect gameplay will be permanent. Like the dash you get at the end of the demo. So no worries there.
I do wish I had more time to add more enemy varieties and looks for areas. I even had pipes for one area but because I pixel arted one of them wrong and didn't have time to fix it I scrapped it till the full game. I will definitely see what I can do with this feedback, thank you!