Up until about 1650, almost all people lived and died within a 50 mile radius of their birthplace. That means people 1000 years ago reproduced in what is called a small breeding population. There was gene flow of course, from other populations.
Now, most of the people in North and South America, and Australia have mixed heritages from populations world-wide. Which means those breeding populations have nearly world-wide scope instead of a 50 mile radius. For example, ~50 Spanish families settled in New Mexico during the 1600's. Most of the men married local pueblo indian women. Now, most of the Spanish folks here from old families have a large percent of their genetic heritage from the Pueblo peoples. This is what gene flow means.
So you can imagine what human genetics are like throughout the Americas and Australia.
I don't think we are anywhere near as "inbred" as you might imagine.