The first mass produced model airplanes were the Skybird wood and metal kits. They installed 1/72 scale as the standard in the 1930s. They also provided many accessories from extra guns and figures to hangers and other buildings.
Frog came along with their early plastic kits before, during and after WWII. Frog stood for "Flies Right Off the Ground", a name which was created for their line of flying models. They needed a name for their new line of 1/72 scale plastic display models. That's where "Frog Penguin" came from. After the war they eventually went to styrene plastic and produced kits for decades.
In the US there was no predominant scale until Airfix and Frog began exporting here. Probably the earliest kits were the Martin Mars and early B-17 in small scales. Hawk started doing more in 1/48, Revell came close to 1/72 on many of their kits before starting a large range in the most popular scale. Aurora stayed with 1/48 with a handful of notable exceptions. Monogram played around in both scales with some of the finest 1/72 scale kits as part of their line.
Airfix had two lines of aircraft kits. Aside from their huge assortment in 1/72 they produced a number of airliners in 1/144.
Hope that this helps a bit.
Tom