No mtnman, never used an atlatl, while I do have lots of arrowheads around, most of them were knapped by indians and found by my Grandfather down in the Texas, New Mexico desert. (He was border patrol)
I have experimented with knapping Obsidion a bit, but I'm far from good at it.
Brain tanning hide, yes, been there done that. Probably won't do it again anytime soon.
Skin a deer, run a trot line, butcher a deer, hog, steer, cut and package for freezing yes.
Make Jerky from scratch sure. I've even butchered out road kill when it was fresh.
I noticed that the oldest of that group was in their mid 40's, with the average 10 years younger than that.
Back when I was that young I did stuff like walking into the woods mid winter for a 2 day camp with only what was in my pockets. Now that I'm 57, I shudder to think about what that would feel like.