Look at my horse...

If you're working on human anatomy, I'd recommend using human references. Unless this piece is just an odd one out in your references with just a horse and house. 

Anyway, for the house, the roof appears squinty. Whenever you draw structures like houses or any cube-ish shape, parallel lines are your best friend. The angles of the roof and wall-panel lines should usually match if they're on the same side. Yours however bend and warp - though this was drawn in a short period which makes the issue understandable. 

If the focal point of the drawing is supposed to be the horse - I'd make it more detailed. The more detailed something is, the more likely it is to stand out rather than blend into the background. 

I really like your squiggly foliage though. It gives your piece a cool illustrative and stylistic feel.

May I give you a hint at the horse? I've been studying horse anatomy and it is tricky. Draw little circles were the joints are at the legs, to guide you. They do bend in strange ways.

If your horse is feeding his neck should be longer and his muzzle should touch the grass. Then the bone in his front shoulder would stand out. Pick a reference photo on Pixabay or Pexels in that pose - it is a common pose - and use it as reference.

I don't hnow how much you want to draw horses, so I'll live it here: https://artincontext.org/how-to-draw-a-horse/ - a very simple, straightforward tutorial.
I have copied all horse pages in "An Atlas of Animal Anatomy for Artists"(I'm doing the whole book actually) and there is no easy way to get it right. Just lots of work. Hope I helped you.