You are overlooking the fact that by the time the gold rush in California happened, the Spanish had been colonizing California since the 16th century and had built a highway system, El Camino Real, which is now a modern road but still there. There was shipping activity at the natural ports of San Diego, Monterey, and San Francisco. It wasn't the frontier. The Oregon Trail brought plenty of people from the east. There were railroads all over the place. And as to craftsmanship, there are and have always been very few artists of Michaelangelo calibre, but they were there. No need to postulate aliens or whatever. It's just hard to get really good when the average lifespan is only about 45, most people die first.
You are overlooking the fact that by the time the gold rush in California happened, the Spanish had been colonizing California since the 16th century and had built a highway system, El Camino Real, which is now a modern road but still there. There was shipping activity at the natural ports of San Diego, Monterey, and San Francisco. It wasn't the frontier. The Oregon Trail brought plenty of people from the east. There were railroads all over the place. And as to craftsmanship, there are and have always been very few artists of Michaelangelo calibre, but they were there. No need to postulate aliens or whatever. It's just hard to get really good when the average lifespan is only about 45, most people die first.