Tools are needed for many buildings, and several units.
The smelting techniques that had been in development in Asia, Africa and Europe since the Bronze Age were never discovered in the Americas. Instead, natives were forced to make their tools from bone, wood or rock. Many native societies thrived despite this lack. Walls built by the Incans remain some of the most well designed in history, metal tools or none. This did mean, however, that arriving Europeans had a wealth of unused ore which they could process, as well as a significant industrial and military advantage over the New World's denizens.