Yeah, Boeing goes way back, to at least 1919. It was originally more famous for its fighters and bombers rather than the airliners. In the 1920's the main US Army fighter (or Pursuit Airplane) was the P-12 biplane. It was also used by the US Navy as the F-4B. Later, Boeing built the P-26 Peashooter.
Boeing's experience of large aircraft grew from its work on heavy bombers (B-15, B-17, B-29, B-50, B-47, B-52). Nearly all its early airliners had some element originally tried on one of its bombers.
When it first flew in the early 1930's, the Boeing 247 was the first all metal, retractable undecarriage, stressed skin monoplane airliner. It was faster than most of the Air Corp's fighters of the day. The 307 was the worlds first pressurised airliner. It used the wings and tail of the B-17. The 377 Stratocruiser was based on the B-29 Superfortress. The 707 had swept wings and podded jet engines mounted on pylons, a layout first tried out on the B-47 Stratojet.
What is interesting is that Boeing could have obtained its world lead in airliner manufacturing as early as the 1930's if it had been prepared to sell some of the early production 247's to airlines other than United. At that time, Boeing was part of a conglomerate called United Aircraft who also owned United Airlines and Pratt & Whitney. The first 60 247's were allocated to United. TWA wanted some but were told they would have to wait until the United order was completed. Well. they were not prepared to wait and so they requested Douglas to come up with a competitor to the 247. This resulted in the one off DC-1 prototype which evolved into the production aircraft, the DC-2 and eventually, the DC-3. The rest, they say, is history.