When pointed out that it wasn't one American but many imported people from around the world then suddenly things shift to "well of course, that's because only the US allows lots of individuals from around the world to work together as a team to do great things".
Which one is it?
In the end it's a definition of how far back you want to look to define "original natives". And the further back you go the more inexact are the "facts". Do we all come from this one place in Africa in the end? Are we 100% Homo sapiens Or How much Neanderthal is in us? Does it depend on which migration wave our ancestors were part of?
Meaning by extension of your logic if I choose the right cutoff Europe is African actually so the Atomic bomb was invented by an African!
Personally I think that the cutoff should be somewhere around second or third generation immigrants. Specifics can depend on how much integration with existing local culture happens or how much individual silo groups cling to their country of origin. And then there's of course the "eradication of previous inhabitants" that sometimes happened. The majority population of the US has roots in Europe, yes. But US culture" is definitely distinct enough now to stand on its own.
It's not as easy as that though on a more philosophical level and from various different angles. E.g. think yourself back to the days those Asian tribes presumably came to America. I read it was three waves. Was the first wave the only true "native Americans" then and the second wave was an immigrant already? That became "native" when and how then? (never mind that there was no such thing as citizenship of a country at that time)