Seems to me that comparing modern game to paleo animals
misses the point. We know that the megafauna had huge fat
reserves, cave art shows us the humps on the mammoths backs.

We should be looking at the remaining mid-sized "mega"
fauna, the musk ox, buffalo, caribou and the like, to make
an educated guess as to the fat content of the extinct ones.
Whole frozen mamoths have been found in the arctic. Anyone
know anything about these?

For those whose ancestors probably lived in these animals
ranges, most North American Indians, Caucasians, and nothern
Asiatics, these would have been the preferred target
animals. Deer, cows, etc were probably second tier targets.

I am assuming of course that paleo people would have eaten
fat if it were available.