For what it's worth, 400 years is about 14 generations, and would constitute several thousand direct ancestors (~ 16K). Even accounting for pedigree collapse over the generations, for the vast majority of (non-Native Americans) Americans only a tiny sliver of those ancestors would have been on the continent at the time, if any.
And? Personal anecdote has no bearing on the question of whether or not foreigners are ethically or morally entitled to immigration and citizenship, or whether the process should be made easier.