The fully mature Bronze Age ended with the 1159 BCE blast that smashed Northern Europe back into a herding culture and ended the sea trade centered on the city state of Atlantis. This mature phase had lasted for at least a millennia and had been preceded by a millennia long expansion of the technology.
The core technology is believed to have originated in Mesopotamia, but I am rather skeptical about that. We have an excellent locale in the Mekong highlands where both metals were richly available literally across the river from each other.
Another issue that I think is under appreciated is the use of copper likely had a very long history that is not visible in the archeological record. The reason for this invisibility is that it represented a convenient medium of exchange and was way too valuable to bury with the dead or even lose track of. Besides that raw copper does rot away pretty well in a few hundred years in any environment that permits water movement.
Think how sharply our understanding of European copper age improved with the recovery of Oetzi with his handy copper axe head and palette of choice stone tools and weapons. This alone ended most of the controversy over the lifeways of the copper age. Scholars have been afraid to use their imaginations and common sense in describing these worlds when all the real evidence simply rots away.
I cannot prove that the natives of New Guinea have been using hardened wood arrows for thousands of years. But the real question needs to be why where they not? A friend of mine has such a bow and arrow set acquired there in the highlands.
The bow is too obvious an invention to not have been made just as soon as someone figured out how to make a bowstring, a much more difficult trick.
The production of copper from a fairly rich ore has been known since antiquity. It takes heat, but not extreme heat and is well within the range produced by charcoal to produce a quality product.
To emphasize this point, the method used by prospectors to evaluate a copper ore in the field was to crush a charge of the ore with some flux in a steel pipe (or pottery retort?) and stick it in the camp fire. This would roast off the sulphur and produce a crude copper slag separation. It is hardly efficient but great for qualifying an ore.
It is pretty obvious that an ancient campfire set with a ring of ore would generate obvious beads of copper in the ash. And just how much of a clue do you need? Again the question needs to be why were they not using copper?
The point that has to be made is that copper is useful and a convenience but not a replacement for an obsidian weapon. It was currency. And that is why so little is found in the archeological record. Just how many present day coins would you find if you chose to dig up a present day graveyard? I have no doubt that outside local barter, copper and then bronze was the principal currency. Homer speaks first of the number of bronze tripods captured. If there ever was an unnecessary luxury usage that is it. Yet it kept your wealth conveniently traveling with you.
Bronze Age culture was rich and palace centered. There is no sense in Europe of a centralized state as in Mesopotamia. There is a sense of a sea borne commonwealth that traded actively with the Americas and there is a sense of advanced antique Indian cultures responding to the influence of these contacts.
We can say that this global trading phenomenon brought about by the necessities of the advent of a bronze based economy, spread a common advanced concept of religion and palace ruler ship around the world. That any of this happened in true isolation is nonsense and reflects only the difficulty in finding actual proof in a background of local artifacts.
What did not particularly happen throughout the Bronze Age was actual colonization. The best recent comparable was the colonization of West Africa. It simply never happened. The only modest attempt appears to have been in New England and it was swiftly overwhelmed and/or absorbed when the trade ended in 1159 BCE.
For a thousand years at least, the sea peoples lived a robust healthy live that allowed them to rove the Atlantic littoral to its fullest. The evidence fully supports that even while it has been studiously ignored. Once again, they could, they should and they did it in far greater strength than I or anyone else originally thought. Once again lack of specific evidence is not evidence of lack and here we have a mountain of specific evidence in every likely prospective location and a few unlikely ones.
I would love to have a European dig come up with an occurrence of maize preferably in southwest Spain just to make that point.