How has recent research changed our view of the origins, migration, and diversification of the Native Americans who were the first to settle the Western Hemisphere?

From the 1930s through the 1990s, the most commonly accepted theory for the peopling of the Americas was the Clovis-First Model. This theory was based on projectile points found near Clovis, New Mexico, that had suggested a widespread Clovis culture across North America. It also suggested that these were the first inhabitants of the continent, having arrived about 11,000 years ago after an opening in the glaciers occurred. In recent years, the Clovis-First Model has been challenged by a number of new findings.
In 1997, radiocarbon dating at an archaeological discovery in Monte Verde, Chile, dates human occupation in the area to about 14,500 years ago, much older than the Clovis model. This alone essentially debunked the older theories.
One newer theory is known as the Coastal Route Theory. It suggests that the earliest peoples to come to the Americas did not wait for the glaciers to melt. Rather, they traveled south along an ice-free route along the Pacific Coast. Since sea levels were lower during the ice age, the route they would have taken is now underwater, making archaeological research nearly impossible. However, geological evidence does exist to show that such a route was possible. It is highly plausible that migrants used this route to enter the continent prior to the melting of the glaciers. However, it remains just a theory.
Perhaps some of the most intriguing new research involves the study of genetics. This new research shows how different native populations diverged and merged over the last 15,000 years. One interesting new finding is that the native populations of the Amazon share certain genetic markers with the native peoples of New Guinea and Australia, suggesting a common ancestry. Just how this information affects the origin theories of the early inhabitants of the hemisphere is not yet clear.
As more information and research technologies emerge, we will likely learn more about the first people in the Americas. What we are repeatedly discovering is that people came to the Americas earlier than previously thought and perhaps from more than one origin.
https://www.nps.gov/bela/learn/historyculture/other-migration-theories.htm