actually, we can have colors as many as we want, There are many Pixelart site that allow such leeway, BUT, here in PJ we give tough love, we need to teach new budding pixel artist some frugality in color number. so you need to learn how to choose and pick your color wisely, and reduce it as low as you can. you're new to this so some leeway will be given, but you can browse PJ gallery and found you can draw beautiful image with less color than 57.

 

my gallery for example https://pixeljoint.com/pixelart/162531.htm I drew this with only 41 colors 

I think I also have a black and white pic for only 13 colors.

 

 

 

Sorry but I can approve this one, it have too much color for a black and white Pixel (57 colors). 

 

this is the link to inspect your pixel.