Early iron tools/weapons were not better than bronze tools/weapons because early iron, non-carburized or alloyed, is softer than bronze. It is, however, much more abundant in most regions of the world. Thus, the cost of iron tools/weapons is much lower. The development of iron weapons required the ability to produce high temperature kilns to melt the iron ore. Early iron smelting was at lower temperatures than optimal, resulting in blooms, agglomerations, of processed iron containing nodules of impurities within the bloom. The process of removing the nodules required hammering the bloom to break up the nodules, reheating the bloom, and hammering the bloom again. This continued until the smith was relatively sure the bloom was pure iron. The process was therefore more labor intensive. The more easily accessible iron surpassed bronze in the Mediterranean when tin trade networks collapsed due to migrations into the area by new peoples, the so called Sea Peoples, which led to the Bronze Age Collapse.
Returning to the cost factor, the armies of the Early Iron Age grew larger than the Bronze Age armies because the cost to equip them dropped substantially. The reason Sub-Saharan Africa developed iron so early was they had less access to tin or arsenical bronze. In the New World, you could have had a culture make the same leap. It would require a sedentary culture with access to high heat kilns and iron ore. Several New World cultures were possible crucibles of such development.
The failure of the Americans to develop iron technology is a fluke in my opinion. All the necessary conditions were present. Small scale iron use was present. No one had taken the leap to develop tools and weapons of iron. Similar to knowledge of the wheel. You can know of something, but not adapt that thing or technology in the same manner as someone else.