It is not clear who was the first to fly an airplane: Richard Pearse, Gustave Whitehead or Orville Wright. Whoever it may have been, the distances of their flights were only about the length of the wingspan of a Boeing 747. They probably never imagined the amount of people an aircraft will be able to carry one day.
The most passengers ever carried on one flight was in 1991 during the Operation Solomon evacuation of Ethiopian Jews during Operation Solomon. 1086 people boarded a 747 in Addis Ababa. When they landed in Jerusalem, there were 1089 passengers. Three babies were born during the flight.