the wee! project is a bit old and gallery standards may have changed since then.
tbh your wee looks like it took very little time or effort to make. if you'd like to improve it there's always the WIP forum, but at a glance I see:
colors hyper-saturated
you didn't stray outside the template at all (not necessary but usually helpful and adds visual interest)
shading on the face is too low contrast to be visible at 1x and doesn't help to define the features.

additionally, it may have been sent back due to a low voting score in the public queue.

most of your art seems to be lacking in very fundamental areas. i won't discourage you from pixelling, but i will say that at this stage in your artistic development daily sketching from observation and practicing the fundamentals in a workable traditional medium like drawing will be the best way for you to build your skills up enough to ensure the work you create will be accepted into the gallery. the WIP forum isn't limited to pixelart, so if you want to post sketches there, you may do so and it may be easier for us to point out where you're going wrong with the fundamentals.

I think you are more hurt than annoyed and I feel for you because since you've joined you have shown interest and get involved. Making WIP threads is the best insurance your work will be added when WIP threads show some level of work, progress and improvement. You do start them but quickly abandon them. Be patient and focused :)