The Americans had more than a little bit to do with the German defeat as well.
A bit, a little bit. While the US definitely made an enormous difference in WW2, I don't feel the same concerning WW1.
WW2: In the Pacific I would rate the US as doing something like 70%-85% of the heavy lifting. In Europe while the British could survive and hold German expansion from going beyond Europe, the US and USSR were the German beaters. Either could defeat the Nazis on their own, though at greater cost, time and blood.
In WW1 what collapsed first was not the German Western Front, but the home front. The British blockade starved the German economy of things like nitrates for fertiliser, leading to food shortages and malnutrition (the neutral Dutch had problems as well). The British and French had by that stage worked out the technology and tactics to finally grind through the trench stalemate. Without the US, a modified version of the Plan 1919 (methodical battle) would have led to German defeat. The final German March 1918
Operation Michael offensive had run out of steam before the US could really make much of an impression. Indeed I have read some authors who suggested that some of the German advances slowed down due to them taking time to loot for food! It did give the British and French a morale boost and permit a safe reorganisation of the British Army, which like the French and Germans earlier, was moving from a 4 battalion brigade (regiments in German, French armies) to a 3 battalion organisation due to manpower shortages. On the other side US entry was demoralising. So while the US did hasten the war's end, Germany was already staring defeat in the face.
So while useful the US effect was not on the scale that it had later in the century. It was only awakening as a superpower.