Lovely pieces! I love seeing people who are not afraid to start from scratch, because 9 out 10 times it helps the image immensely, plus you as an artist get more practice in which is always great 
As to your questions from here.
I know how discouraging it can be, my first attempts over at the old forums went similarly and honestly, getting ignored is easily one of the worst thing for artist motivation that can happen 
. As to "why", there are multiple reasons that I know.
First off, I've noticed in the monthiles over here, the first few weeks people get a lot of replies, but at later weeks, everyone starts working hard on their pieces and not so many people go around commenting. It's often the first impression that makes a topic popular or not and if you don't get noticed from the begging, it can be harder later.
Secondly, people like commenting on what they like. That means that a professional artist with years of practice will always get far more comments that someone still learning (even though they need it the least).
Thirdly, it's a big forum. The topics are updated constantly and with such a flood of new content, it's hard to get noticed easily.
So what can you do?
Here's what I did anyway: Go around and start commenting on topics. That's it. Not the topics that have dozens of replies, but the ones like yourself, with little or no attention (and believe me, you are not the only one struggling with getting noticed). And don't just comment "Nice pic", but try to make a reasonable critique, exactly what you would like to see.
Some of those people will in turn check your topic out, write a critique themselves. After a while, people will start to recognize you as a part of the community and be interested in your work because of you.
At least that worked for me (it even made me a mod! haha)
Hope that helps at least a little bit (:
(I've wanted to write a short critique, but this took much longer than expected, so I'll have to add it later.)
