The answer is Richtofen's head.
1. This is unique in the world of zombies~~ Richthofen has a unique way of looking at things, plus every face is unique.
2. This is abundant in Dead Ops Arcade~~watch video
3. This is where it all began~~zombies were created by Richtofen's imagination and power lust, both of which come from his head
4. This is not a whole- a head is not an entre body, and Richtofen's is missing a few things
5. This is both abstract and concrete~~Obviously a head is concrete but can also be abstract
6. This first appeared in WaW~~ Richtofen was in WaW, so naturally his head was too.
7. This is an Un-inanimate object~~double negative basically meaning it can move, which heads can do.
8. This is composed of organic matter~~Anything living is made of organic matter (carbon based matter)
9. This is a body part~~duh
10. This imaginED zombies; afterWARD it controlled them.~~Richtofen's first name, focus on the caps! At first he imagined them with his head, then in moon he is controlling them with the abstract part of his head. And what else can imagine things besides a head?
11. This can use all 5 senses~~Heads can see, smell, hear, taste, and touch. No other body part can do that! A dead giveaway to the head.
In conclusion, you can use the last 2 clues to put together the answer, Richtofen's head.
Richtofen's head xD