It's definitely much better than your mouse-drawn work. I have a few pointers regarding composition and anatomy, though...

First of all, using gradients for backgrounds is something you don't want to make a habit of (even if it got me through AP Studio Art). However, drawing attention to the right places is something you'll continue to be challenged by. The solution? You need to create a dichotomy of some sort, the best methods being between light and dark or thin and thick. For instance, the one with a gradient background manages to draw attention to the fighter better because the background is darker and characters are, in most places, lighter. The dungeon background does not work as well, however, because the background is the same color and line width as the foreground, making it all blend together and appear confusing.
In short, you made a good choice recognizing the dungeon background didn't work, but rather than replacing it with a gradient entirely you should consider lightening or darkening the dungeon background.
Though, if you're going to cut out the background, make sure you don't miss any places. There's still some "paper" between the arrows on the fighter's shield.

Anyway, as far as anatomy goes, a can point out some major problems with the skeletons (though for the most part, they are just things skeleton-experts will notice). For instance, only the far left one actually has a chin; the rest of them all have their teeth go right to the bottom of their jaw. Also, you forgot to give them sternums (the place the ribs connect in front). Also, keep in mind that the femur and humerus are single bones, while you have them drawn as doubles. The reason forearms and lower legs have two bones is so that wrists and ankles can twist.

The most major thing that needs work, though, is proportions (specifically legs in regards to torso). The length from the hips to the toes is supposed to be about equal to the length from the hips to the top of the head. In other words, if you cut someone in half at the hips, both halves would be the same height. A surprising number of beginning artists mess this up, so you're in good company (though when I was your age I simply covered it up by only drawing Lego people, who have disproportionally short legs).