As I recommended in a recent thread, you should read Lawrence Keeley's War Before Civilization (you can read the preface on Amazon.com for free, I think). He talks about how the myth of a peaceful prehistory has led archaeologists to call many weapons found in burrials "ceremonial" even if they are quite functional as weapons. If the Moche hadn't left their carnage behind for the archaeologists, I have little doubt that they'd be calling the human sacrifices depicted on their pottery as "symbolic" and the actual knives and weapons used, which they have actually found, "ceremonial".
Agreed. Back then, if a man wandered too far from home, he was cut down or enslaved. Thats the way it was in all likelihood.