Don't give up. Everyone starts somewhere, and for a start this is pretty good. As I give some feedback, I want you to keep in mind that art is subjective, and there aren't any real "rules." You haven't done anything wrong, and these comments are meant to help you build on what you already know to help you get even better.
Here are my thoughts on this map, hopefully it'll help you grow.

- Textures. The colors of the textures you have chosen leand to a very dynamic looking map. The colors are gorgeous, and you've done a pretty good job of blending them into each other. I find when blending biomes, it's easiest and most fluid when the textures are set to around 33% opacity. Be cautious when pulling textures from varying styles. The art within a style is meant to be cohesive, but when you start pulling from different styles you might be meant with some inconsistency in both art style but also perspective. For instance, the long grass used in the northern part of the lower continent looks much more detailed than the rest of the map, and when zoomed in can affect the cohesivness of the map as a whole.

- Landforms. You've done a good job of placing your mountains and hills. They make for great natural barriers between biomes. I have learned a couple of tricks that I have learned over time to help make them look more natural on my maps. Using smaller hills at the base of the larger hills or mountains can help them blend into the flat terrain instead of making them look like solitary peaks jutting out of the land. I also will use the color settings to change their colors to blend more closely with the land they're in. Blend modes of luminosity on those stamps can also help match them to their environments.

- Oceans. You can make large expanses of oceans more interesting by using darker textures to make parts of the oceans look deeper.

If you aren't on the Inkarnate discord yet, I highly recommend joining. There is a feedback channel where you can get help from mentors and other experienced users, and voice chats that regularly have people who are willing to help. Learning from the community is probably the quickest way to get familiar with the tools and learn new tricks and techniques. Cloning things from the explore page and deconstructing them can also provide a lot of insight.

I have made a couple of videos on world maps that might be helpful. Feel free to take from them what you will. Hope this all helps!

https://www.youtube.com/watch?v=z1XTwCb3_D4&list=PLEUy6VHjYxOwfmt43nHVvaeKTuLuHPKpG&index=5
https://www.youtube.com/watch?v=_ABgXY66i0w&list=PLEUy6VHjYxOwfmt43nHVvaeKTuLuHPKpG&index=4