Hey King_Fluff,
Map submission requirements have changed a lot since the first maps. If you look at the first accepted maps on the server and the newly accepted maps you can see the difference. It used to be no theme, random blocks, repetitive, but now they are trying to make it better. Getting a map accepted now is much harder than ever before. You need to make sure you have an original theme, not floating islands, one big build, variant blocks, not in clumps, use more than just regular blocks, etc. I know it is sad to see your map denied, but try doing some of the newly accepted maps to see what the map judges are looking for now! Best of luck on your future builds!!