I like the colors and the idea but the mountains seem contrived, as if to separate countries and act as a fence. As a "basis for further work" then this is great - we can tweak it and make something pretty cool. What I would do with the mountains is to not run them all the way to the coast as you have, run them part way and then stick a forest at the end - has the same result of "fence". You could also use a canyon or hills or "wild lands where cannibals live" as barriers. Mountains are the result of colliding tectonic plates (Himalayas, Rockies, Alps) or underlying vulcanism (Hawaii, Iceland), whether in the present or in the past. You don't really need mountains to separate the climates as the desert itself imposes a natural barrier to settlers, and thus nations form outside of it.

The transition from grassland to desert goes through savannah (like the great plains of Africa full of lions and such) and then scrubland (like the American southwest). So you can axe some of those mountains in such areas. From grassland to icecap will go through taiga (coniferous forests) and tundra (cold scrubland). So you can axe some mountains in those areas.

The jungle is in a rain shadow - the area east of mountains that gets little rain due to the mountains blocking it and thus falling on the western side. With that giant desert in the middle there will be no moisture in the air to travel east and fall in that area...just heat. At best it could be grassland if there are some seasonal rains due to wind shift coming in from the southeast (like hurricane season on the US east coast). If the mountains are rather low mountains then it might be deciduous forest similar to the east coast of America but I kinda doubt it due to the vastness of the desert. Now if your planet spins backwards to earth them this would be fine. I would probably move the jungle to the southeast somewhere and swap Harrn and Dalreon.

In the end, these are just suggestions sort of like a simplified crash course on climatology; if you like what you have then keep it - it's your world. And to reiterate, I do like it overall.