Hello Razolo581,
Unfortunately, I will be
Rejecting your map.
The theme is not original, as there are already many rainbow themed maps. Please read over the document in this thread -
https://manacube.com/threads/parkour-list-with-theme.20194/ to make sure your map idea is original.
The build isn't great, as I feel like there isn't really a main build, just small builds complimenting the parkour, which are mainly walls or small boxes. Try to have one main build for the map, that compliments the theme, I would also recommend looking at recent accepted maps, so you can get a good idea of what I mean.
The parkour is repetitive, as it's mainly normal blocks, with some fences, and other jumps. You also grouped your jumps a lot. What I mean by this, is that you would have a sequence of just normal blocks, then just fences, then just slime jumps etc. Try to experiment with a larger variety of blocks and items when building jumps, as well as mixing up the jumps more as well. This will make your map overall more enjoyable to complete.
As there isn't really a main build to this map, almost all of the jumps are floating. Try to avoid having jumps floating over the void where possible, as this can make your map look a bit messy.
The difficulty is good for an easy/medium map, and the length is good for an expert map. Please read over this thread -
https://manacube.com/threads/must-read-map-submission-information-format.649/ to make sure your map fits within the requirements.
Thanks for submitting your map! I hope to see more maps from you in the future.