I think if Woodrow Wilson had gotten his way at the Treay of Versailles and Germany had not been punished for a stupid, costly pointless war everyone in charge in Europe was at fault for, a worldwide depression and the rise of the nazis would have been avoided. World War 2 would either not have occurred, been between the USSR and the west or would have been over something completely different. Maybe Franco loses in Spain, communism takes over there and that leads to showdown between the west and east? It is likely Imperial Japan still invades Manchuria so maybe there is only a pacific war and not a world war. Who knows?
If Germany wins, however, I think everything still plays out badly. I do not think Germany/the Kaiser would have conquered anything (who knows though?) but I think they would have imposed their own unreasonable Treaty of Versailles on France and the UK causing a worldwide depression and possibly a French or English version of Hitler.
For all the hate Woodrow Wilson gets, he was the only one with the vision that tried to prevent a depression and second world war by opposing the unreasonable economic restrictions/requirements France and the UK put on Germany.
Anyway, the US lost a lot of people in the most terrible war in history, the kind George Washington warned us against. My own great grandfather was one of the doughboys that went over, was gassed in the Argonne Forest and suffered from it for the rest of his life. His descriptions of the Battle of the Argonne Forest were quite horrific and the US had 120,000 killed or wounded in that one battle alone. The war and memories of battles like the Argonne Forest caused a strong sense of isolationism that kept us out of the world war we actually needed to be a part of and should have joined sooner.