So, the bottom line is that this was likely either intermittent cannibalism, carried out in times of starvation; or ritualistic cannibalism, in which the meat was removed from the bones as part of a death ritual..
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What was common everywhere in ancient times was human sacrifice.
Human sacrifice is usually fairly simple, because its purpose is just killing, if ritually. But cannibalism is hard work. This is why the bones show a lot of scoring from the meat being removed.