Are there zombies in the Campaign

Well, I found this on Call of Duty Wikia. I think it covers every single possible outcome for the game (here's the direct link to the image).

At the part after you have alerted the whole village, you have to run back.

While you are running, plant the animal traps down. Try to put them near places of cover, as that gives you a high chance of a enemy stepping on them.

The traps are not able to hurt you. Just don't get distracted when placing them.