>US not entering WW1 means the war would have ended anyways in a year or two

That is a fact. US contribution in WW1 was, while very much appreciated, extremely minimal and did not affect the balance of forces that much.

The rest is up to debate.

> That is a fact

We have differing definitions of facts, I guess.

I think not much of a stretch. All nations involved were having problems with mutiny and political turmoil by early 1917. The example of Russia coming apart and being taken over by Bolsheviks was there, and the winter of 1917 plus the Spanish Flu of 1918 made it rather unlikely there would have been a continuation of war in 1919. But, without the American involvement, the French and UK would not have been able to impose reparations, etc.

That WWI and it's peace settlement were a major contributing factor to WWII seems pretty clearly established as well.

> That WWI and it's peace settlement were a major contributing factor to WWII seems pretty clearly established as well.

Sure, but WW2 could very well have started in 1931 or 1953 (just random years) instead, for other reasons. For example, the USSR would have been a much more powerful nation in the 40s and 50s if it wasn't decimated by WW2. And with no presence of US forces in Europe, what would have stopped its expansion but war? Add in communist China and you have the makings for an even more deadly war.

If anything seems like those things would have come sooner, except Germans would have developed nukes first.