I think the best one is, the entire war was an allied propaganda lie.
The US was supposed to be neutral right.
However half the British rifles used in the battle of the Some in 1916 were manufactured in the US, under British license. Opps.
Maybe they belonged to the load of hunting ammunition that the Lusitania was carrying when it blew up, I mean tragically sank in 1915. Opps.
It could be that when Perishing went over to France in 1917, the French were only too happy to equip the American army with French canon. French canon that was made with American steel since 1915. Oops.
Basically we were selling the allies everything that was not nailed down. American Grain, American Steel, American Rifles and small arms. American ammunition, American TNT. It could be by 1917 Americans held 15% of the allied war debt. If the allies lost, we would have been ruined.
It could be that the allies carefully controlled the press, so no one, not even the President of France, knew what was going on. It could be the French, never bothered to count their dead, until after the War. The British did count their dead, but they put such a positive spin on things. German casualties always seemed to be greater than allied casualties.
It could be that the allied propagandist painted the Terrible Hun as a blood soaked monster. It turned out; the Germans were really quite decent. They even led food aid go to Belgium, while their own people went hungry.
It could be we entered the war to make the world safe for democracy, and ended up with the Versailles treaty, which the United States refused to sign.
Many Isolationist felt they had been lied to, too many times.