Yep, in 1950 an airline could choose from airliners offered by Boeing, Douglas, Lockheed, Convair and Martin.
Over the course of the decade, there would also be a number on offer from the UK and France, with the French SUD Caravelle seeing service with United along with the Vickers Viscount, which United inherited from Capital in a merger. There would later be limited numbers of BAC 1-11s and Fokkers in service in this country.
Today, it's pretty much Boeing or Airbus with Embraer playing a minor role.
Bombardier did attempt a mainline aircraft, but while they did actually get it type certified and into production, the financial burden was such that the program was essentially gifted to Airbus and it continues in limited production volume as the A220.