[ggm]

de-fleshing leaves characteristic marks on bone. I believe contemporaneous animal bones show both de-fleshing and bone breaking for marrow. Brains have fats. If you're eating a person, you'd eat the brain (yes, I know ...) if you already ate marrow.

De-fleshing for ritual might not be distinguishable from de-fleshing for food. Except, maybe food would show signs of heating because, 5000 years ago I think they had fire, and fire makes protein yummy.

Lots of cultures in time past (and present?) leave bodies and then collect the bones, clean them up, do ritualised things with them. I think fewer cultures eat their dead, its not unknown, its less common.

I'm not an archeologist. This is just my opinion.