How are you getting 15 colors in the first sprite? I counted about 5 just from eyesight. Same goes for the 2nd sprite. There are a lot of buffer shades but even that can be a 16 color sprite at most.
Other critique I have is that the left one doesn't have much definition in form. It has shading, but still feels quite flat to me.
The right one has form, but how the light is hitting its face seems off, and there seems to be a secondary light source for the boat's side that is facing us (I'm gonna assume that's a boat. Having difficulty being able to tell what something looks like is a critique in itself). Same for the oar behind the character's head, there's a highlight away from where the rest of the light is coming from.
hmmm indeed, you're right about it for about the second sprite, i need to fix them fully and for about the colors in the first sprite, i checked how much i got and it said that i have indeed 16 colors, probably because it have a subtil colors stuff. i will fix it next time.
by the way, i recently redone fully my tileset and i ended up to this version :
so, there how is going the "level" :
well, the tileset was redone because the first version is too long to do so, i indirectly thank to mathias for his interesting tutorial about tileset
next step : paralax picture !
C&C are welcome.