Whenever someone says "you can't "own" an idea," I realized I'm communicating with a jealous retard who's incapable of creative product.
In the example you give, were a flintknapper come up with a new way to knap flint arrows, he would be fed and supported by his community (effectively paid royalties) and the idea would not be shared with other tribes. He would, in essence, own the idea, until he could teach a worthy apprentice the same trick. If that idea were stolen by another tribe, it would be deemed a loss. If it were shared at a council, then an idea or other value would be expected in return.
This is not to say the OP is a clear case one way or the other, or that there aren't issues with IP law. But one can, does, and for a long time have owned ideas.
The only people who argue this want the benefit of others' creativity for their own selfish use, without offering value to the creator.
Also, any cursory reading of history will show that IP, replacing patronage, led to an explosion in arts and sciences.
But hey, feel free to live in your mythical stone age, if it's so wonderful.