First, I'd recommend checking out the relevant section of our FAQs, especially this post.

The main thrust of many of the posts in this section of the FAQs, is that the differences between the Americas and Afro-Eurasia are more superficial than they might first appear.

One of the main differences between European societies and those in the Americas is that Europeans heavily employed iron and steel (which is made from iron) for tools, weapons, and armor. The Americas had their own metallurgy, especially in Mesoamerica and the Andes, but these were largely focused on precious metals like gold and silver rather than iron. This also include metals like platinum that were unheard of in Europe. They produced some quantities of bronze, but it was mainly as subset of the precious metals production (playing around with the ratios of metals in the bronze alloy to make faux-gold and faux-silver, for example) and not focused on making tools. This isn't to say that people in the Americas never made tools and weapons from metals. Between 6000 and 3000 years ago, there was a thriving group of societies in the western Great Lakes known as the Old Copper Complex. This cultures, like their name suggests, utilized the vast reserves of copper in the Upper Peninsula of Michigan to fashion spearheads, knives, fishhooks, and other tools and weapons from copper. Around 3000 years ago, the Old Copper Complex switched to using stone tools and weapons. Why? Because the stone tools and weapons were better. Copper is a relatively soft metal, which makes it easy to work, but less than ideal for something that needs going to be under a lot of stress from regular like a tool. Once long-distance trade became the norm in eastern North America, the Old Copper Complex began important high-quality stone to make better tools and began exporting their copper in the form of jewelry and other ornamental objects. A few copper tools and weapons would continue to be made up to European contact, but these were in the minority.

But why didn't the Old Copper Complex develop bronze like Europeans did? Bronze requires two things. The first is copper, which the Old Copper Complex quite literally had tons of. But it also needs another metal to be added to the alloy, usually tin. Compared to Europe, there's very little accessible tin in the Americas, and the nearest decent source is all the way in northwest Mexico (map. It's not something that was being passed along the trade routes with any regularity to develop a thriving bronze-producing industry.

Additionally, the Old Copper Complex's copper is what's known as "native copper," meaning that is copper in its purest form. It's not an ore, so smelting wasn't necessary to acquire it. How exactly smelting original developed is still an open question, but the best leads we have currently ties it to accidental discoveries related to the production of pottery (people built kilns out of ore-bearing rocks, and the environment in the kilns got hot enough to smelt the metal from the ore). Copper in particular can be smelted pretty easily at comparatively low temperatures, like you make occasionally get while firing pottery. Iron on the other hand requires much hotter temperatures to smelt, and so far as we know today, there's only one area of the world that might have figured out iron smelting before copper smelting (West Africa). Without smelters already producing copper, it's unlikely that you'd accidentally produce the temperatures necessary in the necessary environment to produce iron. Unlike copper, iron is exceptionally rare in its native form. The only real source of native iron comes from meteors, which provided the iron used in the Arctic iron trade (where it was made into knives), and the occasional bits of iron we find in eastern North America which were made into beads and chisels. But meteors don't provide enough iron to build a reliable iron-working industry upon.

All that said, the stone weapons and tools used by Native people shouldn't be regarded as primitive. They'd been developing for thousands of years just like Europe's metal weapons. The Aztecs are rather famous for their macahuitl, a stone-edged sword capable of decapitating a horse. The Apalachee of northeastern Florida harried the Spanish out of their territory with bows that fired faster and more accurately than contemporary firearms (which were notoriously slow anyhow), firing arrows that could puncture multiple layers of Spanish chainmail.

Of course, while stone has its advantages compared to copper, it also has its disadvantages compared to iron and steel. You could get a sharper edge out of something like obsidian, but its fragile and would need to be replaced regularly. Iron might not be as sharp, but it gets the job done just as well and is more durable. Once Europeans arrive and can provide a reliable supply of iron, stone tools and weapons are largely phased out during the colonial era.

Going back to firearms for a moment, this is another aspect of European technology that is often pointed to when people say that American technology was "behind." It's important to remember the unique history of firearm development. By the time Europeans arrived in the Americas to stay (so ignoring the Norse for the moment), they had only had firearms for about 200 years at most. The technology had been brought west relatively recently, likely by the spread of the Mongols across Asia and into Europe. The development of firearms is predicated on the invention of gunpowder, which Chinese alchemists invented in the 9th Century while researching an entirely unrelated field. It was a fortunate accident for them, that had huge potential for military application. It's not at all surprising that societies far removed from China had not heard of gunpowder yet, nor had they (or Europeans for that matter) chanced upon the right combination of ingredients to make it themselves without first being instructed by others. Soon after the English arrived in New England however, the Narragansett of what's now Rhode Island began establishing their own forges for maintaining their firearms and supplying themselves with ammunition. They still relied on the English for gunpowder (though they had sought to learn the secrets of its production), but no one in New England could make it at the time - all the gunpowder was being imported from England until after King Philip's War in 1675, during which the Narragansett gun forges were a primary target by colonists. In general, though, until the mid-1600s Native American societies ignored the gun, and regarded their own weapons as superior (as the Apalachee demonstrated against the Spanish). It wasn't until the development of flintlock rifles that firearms became popular among Native societies in eastern North America; during the aforementioned King Philip's War, most of the Wampanoag and Narrangansett warriors were armed with flintlocks while their colonial counterparts largely were using older matchlocks, flipping the usual narrative of which side possessed the more advanced weaponry.