it's pretty amusing to notice, that your dirt tiles are actually more repetitive and brick-like that your brick tiles.
IF you really ARE going for simplicity, drop that idea of texturizing the whole foreground.
it IS ok to leave large gaps of just basic colors, design your tiles to serve only as variation among a vast amount of just a flat color, that will look both more vivid and varied, and convey a simpler look.
by the way, dont limit yourself so much about having everything be simplistic, look at mario 3, the look is very simplistic but that doesnt keep them from making the wooden ships look rightfully wooden. or if you are looking for something more modern there is Boktai, the complexity is entirely dependant of what the context requires, dont dumb down your game by conveying poorly your simplicity premise
if you imply something should be of a certain material, go trough the full implications of that promise and make it look like that material.
