There have been several fictional interpretations of what a zombie is, how scary they are, and how they can be killed. These interpretations range from normal people unwittingly compelled to do evil at the behest of some kind of evil magic to shambling monsters with intact consumer instincts. I am not going to lie and claim that I have seen all the zombie films or media ever made, but I have seen several of them (I do still want to see this one). Therefore I am absolutely unqualified (although I assert that I don't need qualification to speculate upon fiction) to offer my commentary.
OK, I just started poking around the Internet and suddenly realized that I need to do more research before I can offer anything worthwhile for zombie biology. Meanwhile, I offer you my favorite short zombie comic story (the premise basically revolves around a bad-ass dentist who feels he is responsible for eradicating the undead hordes because zombies naturally rose every 100 years and dentists were the ones who made sure that most everyone in the last several decades died with intact teeth). It should be noted that the rest of the anthology is also quite good, especially "Daddy Smells Different". My favorite long zombie comic story depends on whether or not one would consider a sentient corpse-possessing squid-fighting worm to be a zombie. Actually, I guess one couldn't consider that as such because Wormwood lives on beer and not human flesh. So my favorite long zombie comic story is definitely Chris Ryall and Ashley Woods' Zombies vs. Robots (I will soon purchase Zombies vs. Robots vs. Amazons).
I don't know exactly why I shared any of that. Maybe I'm subconsciously trying to improve my geek street cred?