Zombies are not my thing. As a child, I avoided the undead in my Dungeons & Dragons world for power-hungry humans, elves, or orcs. Evil is not mindless and faceless. It does not rise from the dead, but forms in the living.
Because zombies do not interest me, I have not read The Walking Dead comics and will avoid comparisons to the original work, but I will take a Bowie Knife stab at the walkers.
There are a hundred themes in The Walking Dead. Someone has a class on all of them. I think all themes roll up into a big one I call Happiness and Truth.