The U.S. for example. At what point are the Americans born there counted as natives? We don't call other countries by their "pre-conquered" names, so at what point are people born in America, native Americans?
I hope this isn't coming off wrong, I'm just genuinely curious as to why we don't considered Americans born in America natives. It's been almost 400 years and people still aren't counted as "Americans".
Not to take away from any new responses to your question, but you might be interested in this answer from a month ago: Why are there so few indigenous peoples in Europe?, which talks about when peoples are considered indigenous in the US and elsewhere.