Considering the fact that Ust'-Ishim is equally similar to all Asian and Native American populations and equally similar to the two ancient genomes, Fu and colleagues write this:
This suggests that the population to which the Ust’- Ishim individual belonged diverged from the ancestors of present-day West Eurasian and East Eurasian populations before—or simultaneously with—their divergence from each other.
I would give a strong interpretation to this. It seems unlikely that Chinese (Han) and Andaman Island (Onge) populations could be uniquely descended from this ancient Siberian individual, so Ust'-Ishim is not at the stem of the later diversification of Eurasian people. That means that these later people derive from a
different group than that represented by Ust'-Ishim. The initial dispersal of humans into Eurasia contained at least one dead-end population that contributed at most some very small amount of ancestry to living people.