sorry.. i got the comment... this is mostly just for fun.
Nobody posts here to try to be a hammer on the new people, they post to help. The comment wasn't meant to detour your fun, but to make things more enjoyable. Making 16x15 sprites can be fun, but making definitive, clear, and just overall better looking and improved sprites is even better. And I agree with the contrast comment, add more contrast to the sprites and you will be able to define the features of the sprites a lot more, because in such a small space with not much room for outlines, contrast is all that's going to help you do that.
Comments may be blunt and to the point sometimes, but helping art isn't always about being nice, but honest. I've been here since the pixelation days, and I've gotten the same comments as well, but it only helps you in the long run.