You ought to take a look at the maps. The only "German" territory that went in to Polish hands after the First World War was the very narrow Danzig Corridor that gave Poland access to the Baltic. Germany maintained East Prussia.
95% of pre WWII Poland were Polish speaking lands that were previously part of the Russian Empire before the 1917 Revolution. The Poles fought Lenin's Red Army for their independence in 1919/20 and won.
Europe, 1914
Europe 1939
Thanks for the pictorial confirmation of my point.