[RossA]

Learn some math. Charlemagne lived 1200 years ago. That’s roughly 40 generations. So you had 2**40 (about 1 trillion) ancesors...far more than the population of the world today. So each of us is a descendant of Charlemagne many, many times. Similarly most English speakers are descendants of Henry VIII...but none of the first Queen Elizabeth.

[Trapped Behind Enemy Lines]

I’m not sure Henry VIII has any living descendants.

His three children, Edward VI, Mary I, and Elizabeth I, all died childless.

Henry VIII did have one known bastard son, but he also died childless at the age of 17.

The English monarchs who reign today are all descended from Henry VII and Henry VIII’s sister.

[Vigilanteman]

The greatest share of that one trillion is duplicated. England was home to a mere 2.8 million people at the reign of Henry VIII. Do the math just back that far, 500 years or so, and your potential ancestors are many times the population of England . . . or even England and several neighboring countries.

For most of earth's history, our TOTAL population has ranged within 15% or so of a half billion people. It was only the invention of capitalism and the industrial revolution which led to the planet's capability of supporting many times that number.