I think the zombie thing is largely about what is going on in the minds/spirits of humans, and possibly other earth's creatures. Consider the fact that human body is just a house/vessel for his spirit(the real human) to live in and operate on earth, which evil spirit also use as home to live & operate in when the real owner of the house/vessel is asleep or dead. Evil spirits are controlled by satan who uses them to operate/move the human bodies like zombies.
It's important to note that Zombie & Vampire are similar. Both need blood to survive... And according to the Word of GOD "There is Life in the Blood"
The infected humans would either drink actual blood to feel alive or suck life out of people through their words/deeds. There is a reason why a lot of people feel better when other humans are hurt by their hurtful Words.
Way back in the beginning of the Bible, Adam and Eve sinned by eating the fruit. Then they realized they were naked, and sewed fig leaves together to cover themselves. They hid from the Lord as He walked in the Garden in the cool of the day.
Personally, I think that Adam and Eve change physically as well as spiritually. After all, a husband and wife are almost required to be naked in front of each other, just so they can help the other through friendly, bodily examination. So, what's with A & E? They changed physically.
As their offspring, we're all zombies through them.