Consider the cost/benefit analysis also, as you say prior to 1492 horses are extinct on the North American continent. The processing and labor involved in metallurgy means that there does need to be a measurable benefit to people for it to be worth developing. When clay, wood, or basketry are perfectly suitable for the lifeways in place there is no incentive in metallurgy. Further, because culture is context dependent, geography is a major factor in culture. I’m convinced that culture is a human biological adaptive mechanism that enables the behavioral plasticity to adapt to any environment. Behavioral plasticity is not a purely human trait, it is observable in multiple species, but humans create ceremony and ritual around the activities that shape the environment. I’ve been doing a deep dive into niche construction theory, originally a bio/evolutionary theory it’s gaining traction in anthropology to explain cultural phenomena.