I suppose we do consider Pilgrims and Christopher Columbus to be part of our shared American history even though they technically pre-date “America”.
I think it’s less about “how far back in history” than it is being able to trace some sort of connection to that history.
So, only 34% in USD? 
This, really. Which varies greatly from nation to nation and ethnic group to ethnic group.
My ancestors came to what is now Massachusetts in 1635. Not much before that the population of the area looked significantly different.
Modern Egyptian currency features images of art or monuments from ancient Egypt.
Fortunately Christopher Columbus didn’t stick around. Spain likes to celebrate him, though.
Latecomer. My ancestors were there a whole 15 years earlier.
I do find it interesting that both my British ancestors (1620) and Swiss ancestors (approximately 1599) fled their respective countries to escape religious persecution. Oddly enough the people who have live in Switzerland for generations seems to have less interest in tracing their distant (let’s say more than 200 years) ancestors than many Americans.
I can’t take credit for what my ancestors did. I can still be impressed that they did what they did.
Not particularly. We do celebrate what used to be called Día del Descubrimiento or Día de la Raza or Día de la Hispanidad: Discovery Day, Day of Hispanic Culture or, well, Day of Hispanic Culture. Nowadays we just call it “October 12”.
Absolutely. And so can we all. We can all be impressed by what your ancestors did, and by what other historical people have done, just as we can all marvel at the pyramids and the level of dedication and ingenuity that must have gone into creating them. But the credit belongs to those long buried, or scattered to the wind. Nobody alive today gets credit for them (unless you’re one of those racists who believe the pyramids are evidence that some races are better than others, and that “back in the day” your preferred race was the one that lived over/ruled in that area, damn the historical and archeological record—in which case, I probably find your racial theories most objectionable, but your pseudo-historical views are also of concern).
I recall Robert Heinlein writing of the iguana who bragged his grandfather was a T.Rex.
Genealogy charts show I’m cousin to various Wild West figures. Yippy tie one on!
My ancestors lived long enough to let me infest the planet. Thanks, folks.