I see this over and over again with newer students. When trying to decide what they want to paint or draw next, they look for something that is “easy” enough for them to do. There are a couple of problems with this way of thinking.
Things that look simple tend to be more difficult to make look good. Paintings with a lot of detail and busyness are easier just in that you can cover mistakes with some of that busy detail. You also don’t notice minor mistakes in something that has a lot of busyness to look at. I’m not saying you shouldn’t try the simple things too, but don’t avoid the stuff that looks more difficult just because it has that extra detail.
In this first painting, there is much less detail. Much of the background is just a gradient of greys and whites.
This second painting has a LOT of detail. More time consuming yes, however it was fairly forgiving when a mistake happened. I could thrown an extra ripple in the water to cover a problem with a fish, or a tree branch where the sky had an issue in blending. With the painting above, any mistakes in that background stand out like a sore thumb (which seems like a silly saying given I have yet to see a sore thumb really stand out at any point in my life).
When I first started painting I would copy the dolphins and whales painted by a well known marine artist. I knew his paintings weren’t very realistic but I felt I wasn’t good enough to try anything more advanced. Finally I started modeling my work after an artist who knew the anatomy of sea life and had such detail and amazing lighting I was hesitant to try. While my work was clearly not as good as the second artist, I had shot up several levels over the work I was seeing from the first. Don’t limit yourself to something that you feel is a beginners level just because your work isn’t as good yet. Try something more difficult and see how much better you can do!
Something I should add to this however is don’t skip the basics. Study lighting, contrast, perspective, anatomy and such while you are trying to paint the stuff you thought was too hard. Those things are still building blocks to a great artist.