If Elon Musk did colonize Mars with 1 million people, would he be the most important person to have ever lived?
I would then think of him like maybe Christopher Columbus, or the Pilgrims from England that started populating North America. Outside North America these people are not seen as important (or even known). Schools in other parts of the world don’t teach much about this.
Here in America, however, we have Columbus day to remember the crossing of the Atlantic in 1492 by Christopher Columbus, and Plymouth Rock in Massachusetts to remember the first landing of the Pilgrims who came from Plymouth, England. We have Thanksgiving to remember a mutual celebration between the Pilgrims and the local Native Americans after the Pilgrims had their first successful growing season.
So I would say that to the people of Earth Elon Musk would not be the most important person to have ever lived, but to the people of Mars he would be the most important person for the first few generations, but as time passed he would be seen from an historical point of view and remembered on future Martian calendars by the people of Mars.
Here on Earth he would be remembered in history books, too, but so many people have come and gone in the history of mankind. Many people in the past have been very transformative, but overall are not seen as the most important persons. People like Alexander the Great, Issac Newton, Albert Einstein, Walt Disney, George Washington, Queen Victoria, ad infinitum, have all been very important in the history of mankind, but none stand out over time as the most important person to have ever lived. So will it be with Elon Musk even if he did colonize 1 million people on Mars.