Technically what we call world war 1 and 2 were the same war with a 20 year pause in between. If the entente in 1918 had invaded imperial Germany in 1919 then no stan in the back and no nazis.
And there were two world wars before 1914: the war of Spanish succession (the French and indian war was the north american chunk of it and there were wars in Asia) and the Napoleonic wars were fought in 3 continents
Hardly. There were no Geneva Convention treaties in WWI. People in WWI weren't thrown out of their jobs because of their religion, nor were they rounded up and put in cattle cars, shot on arrival at a concentration camp, or allowed to starve to death working for the Reich. Nor was the property, wealth and art of people stolen from them in WWI. Germany held elections in WWI, but not in WWII. Germany wasn't divided after WWI, although it probably should have been, then maybe Hitler would have never come to power.