Yo! Welcome to pixelation.
Your first two pieces are pretty good imo, although the front wheel of the motorcycle could benefit from a more circular shape.
As for the gang members, and their rigid poses. The best way to alleviate those problems is to practice anatomy any chance you get, and base poses off reference images until you get the skills necessary to create your own poses. To be honest, dynamic poses are something that I still struggle with. But, I've been practicing sketching a lot of different poses lately, and I can start to see it all coming together. The first of the gang members looks especially problematic with its noodly arms, and relatively undefined legs. I owe you an edit with the chain guy, so maybe I'll take on that first member too. The third member (although lacking his right shoulder) seems to be pretty well defined in comparison.
When I started doing some suggestive edits on the zeppelin, I got a bit carried away. If I had more time, I think I may have colored it all. It's a pretty impressive/inspiring piece, so take that as a compliment. The first thing I did was to redefine the shape of the turbine on the left. While it looks good in the line art, when shading it becomes apparent that there is not much rhyme or reason to it. AFAIK anyways. After that I just started shading it with colors from your piece, introducing my own and replacing yours as I deemed it necessary. In the end, I got the palette down to 11 colors, and then threw in 3 more (the red to oranges) to ensure that I had every color needed to replicate the colors you had already layed down. I ended up using a fair amount of grays, and it's probably good for you to know that grays can operate like a wild color if you can modify your colored ramps to accept them. Which isn't too much harder than cutting down on the saturation a bit. I realize now that my edit doesn't match the style you've already established, but it's worth noting that it could easily adopt to that style with the inclusion of maybe 1 or 2 colors. At that point, you'd still have a 16 color palette-- 2 less than what the original line art was at. You seem to have a pretty good grasp of shading, and lightsources, so I'm not going to expand on those areas very much. I'll just say that contrast is very important, and don't shade something unless it is doing something to help define the shape of whatever you're shading.
I AA'd your zeppelin to the bg in some spots. I just did it cuz it's fun, and it was the easiest way to get your variable thickness lines looking smooth.
Also, pixelation has a built-in zoom function, so there's no need to display things at 2x or whatever.