In reply to Cú Chullain:
Well this has distracted me from work quite nicely....
Initially my thought was "not much". For example I know how a gun works, and that requires some metal work, and I could probably work out the bits of producing metal from ores...I think I know enough to with some trial and error extract useful ore from the ground too. But I've no idea how I'd fine the ore to start with.
Gunpowder (or similar fast burning/explosive stuff) I could probably work out...if I had any idea where to get the basic ingredients from in the first place!
but then I got thinking more and figure I know enough basic engineering (pulleys, the feckin wheel, water wheels and wind mills) to find numerous ways to automate or make more efficient a lot of things.
Building, I could make crude bricks and mortar and know enough woodwork (which I could botch together without sophisticated tools) to improve living conditions and defence.
I could make some small but noticeable advances in agriculture.
I can get a fire started with the old two sticks method, though it's hard work, but with a flint (how to find flint I'd struggle with tbh but once I'd got some...) can do it pretty easily.
Weapons - obviously some trial and error but I could fashion a crude bow, and they'd already have spears and the like. I also understand enough about warfare (basically tactically working as a group) that my tribe would be able to beat the undisciplined rivals.
hygiene and sanitation too.
So I can vastly improve the hardships of safe shelter, adequate food, safety from other men. And once they're gone other things can develop naturally more easily as there's time for them to do so rather than all day spent trying to stay alive.
By adding basic economics, mathematics and writing into the mix I think I could give a good basis for them to build on. So in my (nicely extended) lifetime I wouldn't make THAT much difference, but I'd speed up the steps of getting the basic building blocks of society in place from which development can then speed up.
Ah that's better. Don't feel totally retarded now....
obviously I'd be reliant on them at first on how to stay alive without so many things I'm used to.