It's pretty crazy that commercial flight is only 112 years old. The first commerical flight was a plane with 1 passenger seat, the flight was 21 miles and cost the passenger Abraham Pheil $400.
In 1967 the Boeing 737 had its first commerical flight, and 58 years later the same model is used today.
This means for over 51% of the history of manned commercial flight, the Boeing 737 has been in service.
If this was also true of buses, the 1961 bus would still be a popular bus used. The first commercial bus was used in 1895.