Heya Marfield!
I shall be giving my opinion here if you don't mind; just a heads up,
I am not a map judge, this is just my personal opinion!
The THEME of your map is unoriginal as we already have a large Minecraft blocks map on Manacube. When coming up with a theme I'd advise you to check over this document here:
Maps List - this shows all the accepted maps on ManaCube to date, with their themes to allow you to see if a theme is already on the server.
The BUILD sadly counts as 3D pixel art; maps that are 3D pixel art are not accepted on ManaCube anymore. When coming up with a building design try to make it unique and as distinct as possible, ensure that lots of detail and depth are added as well.
The PARKOUR matches the difficulty just fine, same with the length! However, make sure the parkour jump variation is consistent throughout and don't clump it together. I'd recommend you check this document here:
Jump Variation - this will allow you to grasp a better understanding of what I mean by jump/block variation.
Anyways, that is all! I hope I helped you with your map <3
Cheers!