The pop culture depiction of weapons in pre-metal cultures tends to be a bunch of people running around smashing each others heads in with glorified stone clubs and jabbing with pointy sticks, before suddenly inventing swords. How accurate is this? Were "late model" nonmetal weapons really still that primitive? Given mankind's propensity for ingenuity I find it hard to believe, especially when it comes to cultures like the Native Americans (who were fairly sophisticated relatively speaking). What were weapons really like just before the transition started?
It's valuable to keep in mind that until maybe three hundred years ago, the pointy stick has been humanity's signature weapon. You can take a sturdy tree branch and sharpen the end and it's great because you can stick your enemy or your dinner in the guts from far enough away that maybe he can't stick you back. Then maybe you figure out that if you cook the point over a fire without letting it char it gets much harder, which makes it more effective. If you're really inventive you start playing around with blades napped out of flint or chert or obsidian, and then lash one onto the end of your stick with some animal sinew or plant fiber and now you have a spear as sharp as anything anyone could make out of metal for many thousands of years.
The one really big advantage metal weapons have over ones made of stone is that metal is much more durable. You're excellent at napping so your obsidian spearhead may have an edge only a couple dozen molecules wide (much sharper than anything you could attain with copper or bronze or iron), but if when you're thrusting it into someone or something you accidentally hit bone, it's broken. Metal is much more forgiving of that. It also has mechanical properties that make possible things like swords that the brittleness of stone make impractical. Early on when people were first figuring out how to smelt copper ore, a metal weapon wouldn't necessarily be any deadlier than a stone one, but it would be way more robust. This is a huge advantage all on its own; after all there's a reason why metalworking became a thing, but the improvements the practice introduced were much more iterative than they were revolutionary.
I kinda came at your question from a direction you weren't asking about, but I hope it's a useful answer anyway
hi! Substances such as stone, bone, antler, tooth (e.g. sharktooth), and shell can all be used to make sharp points/edges, so weapons like darts, arrows, knives, daggers, swords, lances, spears, and harpoons are all possible without metal. Since you mention Native American weapons, I took a quick look for previous discussions; I'm sure I've missed some good ones, but here are some to get you started:
is it true pre-columbian native Americans, had no weapons made of anything better then Obsidian? - includes a link to a video demonstration
Do we have any idea as to what the noisy weapon used by the natives in the Vinland Sagas is?
if anyone can remember others, please reply with links - thanks!
not quite on topic, but the following post contains a round-up of posts on Native American armour, which may be useful for visualizing warfare, and includes the odd mention of weapons
lastly, and straying even further off-topic, the FAQ has a section on metalworking in the Americas; a few alternative materials are mentioned