I am not an expert at doing parkour maps, nor am I particularly good at parkour so take everything I say with quite a bit of salt.
The theme seems unoriginal as floating trees and ruins (similar to towers, castles, etc.) have been very overused.
The build it not great. While it is clear that there has been significant effort to add personal touches and minor elements (especially to the tree platform), the ruin is still mostly a blank box. Techniques like framing and depth would really help to bring this to life!
The parkour jumps themselves look quite varied but do not use a variety of blocks that parkourists (I don't think that is a word) like to see. Things like trapdoors, piston heads, enchanting tables, flower pots, heads, etc. Additionally, most of the jumps are floating which does not reinforce the story the build is trying to tell.
Finally, the number of jumps is a tad long for the easy difficulty but not unreasonably so.
It is clear that there was a lot of effort going into this, but by having people test your map and give suggestions, I think you could have a much better product!