Unfortunately the things I'm going to suggest are going to be what you don't want to do. These things are colour theory, perspective and life art studies.
I'm not sure whether you're doing this as a hobby or if you're doing it as a hobby but also want to progress as an artist. So I'll keep my suggestions somewhat short.
First off, with regards to how you presented your current ability to us, I like it. The faces have some good ol' Western personality in them, so yay!
Colour theory will fix your mind block in regards to the colours, you'll find out what colour complements the other, what tones of the same colour you can use for foreground and backgrounds, it's pretty boring stuff but it's unfortunately what you'll need to know if you want to really pick up what to use in foregrounds and backgrounds. For example that seems like a desert scene, you could use harsh reds and yellows for the dustburnt wood and harsh sun, and then you could contrast that with some pastel blues in the shadows to give it some depth and give the shade a feeling of respite. Wanky shit, I know, but even to a lay person it just "looks better".
At the moment, in regards to colour, it has made your piece look slightly flat due to the same colour and shade in foreground and background. You could try throw some pastel type colours over the entire background but that may make it too dark and become the focus point. Alternatively you could make thicker linework on the dude and building in the foreground to make them feel stronger to the eye.
With regards to perspective; Another thing I notice is the lack of focal point, the perspective looks like it would end in many areas, rather than just a few focal points. That would make the background look closer than you would desire too. So studying focal points and starting with a few, or even one focal point to get a perspective of where buildings and landscapes would be in proportion to everything else would help you too, I think.
Finally life art studies, probably not something you're interested in at all. But if you really want to progress into making very animated and personable cartoons, the background in understanding anatomy, bone structure, muscle movement and everything else will benefit you more than you think.
I am a huge Japanese manga and animation nerd, and when I discovered such a thing at an early age I actually set myself back a few steps by drawing such exaggerated cartoons. I didn't have the basic understanding of the rules enough for me to break those rules, so things just ended up looking... not right. I mean I would tape Sailor Moon when I was like 13 and pause frames and draw them, they would come out fine but if I tried to do something from memory, they'd look slightly downy.
My currently images don't really resemble Japanese art but if I were to try bust out some ultra cartoony manga dude right now I would be confident in nailing it pretty well because of all those hard yards I put in on life study.
You're not terrible at art, not by a long shot and it's awesome to see you playing with colour as well. If you want to just do what you're doing now, you could get away with using reference images from Google and get better slightly over time, but if it's something you think you really want to get in to, then the techniques above will shoot you to the starts and you'll literally only be limited to your imagination.
Don't get discouraged from this wall of text either. It's never too late to learn. Speed3D from this forum started learning art at a later age and his stuff now is fantastic!!
Anyway, hope this helps - sorry, I don't really do TL;DRs D: If you have any other questions I'm happy to help, or bust out the wacom and give you examples etc
Also don't say it's not art, it's definitely art and you shouldn't feel like you can't call it that!