Hello! I've played your parkour and wanted to express my thoughts about it.
The build itself seems rather
not original, since there are already
many maps that are either island or cave themed (
ShatteredWorld, GoldminePK, Western, BiomesPK, Tropics, so on and so forth blah blah blah) which makes the map seem uncreative.
Try coming up with a concept related to your theme that hasn't been done yet. For example, your theme are floating caves in this scenario. You could make a big floating island and make different cave layers inside of it, kinda like multiple geode's and every stage would vary from one another in terms of its playability, but also its looks.
The parkour itself seems rather
not varied, with focusing mainly on standard block jumps, ladders and fences, which
may feel quite repetitive. Personally I like these kinds of parkour maps, since they remind me of old maps. However, if you wish to have your map accepted, you should
consider adding more gameplay mechanics to your parkour. Most basic examples would probably be
heads, pistons, minecarts, water/lava jumps. If you are feeling quite fancy,
you could also do some redstone puzzles, which when done correctly can really boost up the enjoyability. Also, remember to
make some of your parkour pathing inside a certain structure, so it's not all outside. Making a main build makes it easier for your parkour to build itself out of it.
Overall I'd say that
the build and the pk are nothing special, but with some upgrades and tuning everything can be done much better. It's okay if you're not gonna nail it the first time, especially with today's submission standards. If you need some extra help, I'll send a link below that might give out some advice for you on your journey of building future maps if you wish to continue.
I'll be happy to help if needed and can't wait to see more from you!
Don't give up!
Map making guide: https://manacube.wiki/parkour/making-maps/parkour-maps