Hey, man, I did a small edit on your barrel to point some stuff out. here we go:
Thw two major things were perspective and detail. I assumed you were going for a standard "JRPG-top-down" perspective and rounded out the shape of the barrel accordingly. The biggest thing was that the shape of the metal ties didn't conform to the shape of the barrel's top and made things look a bit wonky.
The second thing was that the brightest colour on the top of the barrel made things look over detailed or cluttered or something, so I just did away with it, which I think cleans the look up considerably. One of the more common mistake made by people new to pixel art is trying to cram too much into a small space, leading to less readable sprites.
Other than that, you seem to be going in the right direction. Good colours, good contrast. Give animating your sprites a go, and see where that leads!