Bill already gave some excellent critique, so I don’t have much to add.
As for as the concept behind the series you’re working on, I already told you my opinion in your Superman thread–that the concept isn’t compelling and doesn’t really have a point in the first place, despite how you try to explain your attempt to do something different and unique. Different doesn’t automatically mean it’ll be great.
As a visual storyteller, you need to have a compelling theme worthy of exploring, and your idea of showing various superheroes with their heads cropped off, so that we only see their bodies, thus evoking some kind of resonance in our recognition of them as symbols, is a flawed one (IMO). It’s a moot point to be made, because the attempt to distill superheroes down to their symbolic significance has already been done to death in comic books–particular comic book cover illustrations. We can see this almost every month on at least one comic book cover that’s published, and there have been countless covers playing with this idea, and most are done much better, because the artist understands where the graphic power actually comes from, and that the real symbol here is the costume itself, regardless of who’s wearing it, or even if there’s a body to put it on.
Superhero’s costume hanging in a closet among mundane objects we’d see in any typical household, or discarded on the tiled bathroom floor amongst blood stains and bandages, or stuffed into a gym bag on top of the backseat of a car next to children’s stuffed animals, or hung on the back of a dining room chair with bills, bank statements, and junk mail–all of these are more emotionally/intellectually resonant approaches than what you’re doing with the purposely cropped off heads.
The challenge for intelligent storytellers, isn’t just finding a theme/motif, but also to execute/implement/convey the themes and motifs in ways that are compelling and thought-provoking.
With all that said, I personally would never reject a submission due to subject matter/style (unless it’s very offensive). I’m just sharing my point of view on what constitutes good visual storytelling, and I hope that despite your feelings of indignation, you can appreciate what I’m trying to explain to you (which I think will help you as a visual artist/storyteller in the long run).