They also had metalworking, it just wasn’t iron and in many cases it made no sense to use metal instead of naturally occurring materials with many of the same properties, like obsidian (you can actually make it sharper than a scalpel). It has disadvantages of course, but so does iron; it rusts and requires a ton of energy to create.

The idea that metalworking is somehow a ‘peak’ of civilization was derived from 1800s anthropology trying to divide societies according to how ‘advanced’ (read: similar to European technological development) they were. In many ways some Indigenous American technologies surpassed European ones: ex, land management. When Europeans were destroying every old growth forest they had, some Indigenous American nations were so adept at land management they managed to have settled hunter-gatherers (coastal PNW). As in, these hunter-gatherers didn’t need to move constantly about the landscape to hunt because they maintained it to be bountiful, and still managed to have population centers of similar size as many European ones.

You’ve also got terra preta in South America, which transformed poor quality soil into soil that made horticulture possible. And as long as we’re in Central and South America, one of the first nanotechnologies is believed to be a paint made by the Maya called Maya blue.