The role of the US in WWII is always grossly exaggerated.
WWII was a slugfest between two totalitarian regimes, Germany and USSR, conducted using troops that were, in the majority, neither Russian nor German, but slaves of one and then the other, and then, typically, executed.
The Western front was a sideshow. Stalin could easily have rolled over all of Europe, but stopped short for reasons known only to him.
The US accounted for significant portions of the USSRs vehicle fleet as well as provisioning. The USSR fought Germany, but the US defeated Germany. It wasn't fair; war never is.
The US sent 400,000 trucks, 350,000 tons of explosives, 3m tons of petroleum, 4.5m tons of food, 3000 ship engines, and 2000 locomotives in through Iran, and corresponding amounts of other supplies. But Russia had already pushed Germany much of the way out by the time the stuff arrived in any volume.
For all that, it added only 20% to their own production, food possibly excepted. Russia made a point of acknowledging the food, and the trucks were maintained for long afterward.
To be fair, the Soviets are directly responsible for arming the Third Reich. They created the monster and then they had to put it down. People always forget the cross border training and massive amount of raw and finished goods transfered from Russia to Germany.
That is said, but without both British intelligence and American steel, the result would be largely the same. And the blood wasn't mostly Russian, although it was sent into combat by Russians.
Maybe the British intelligence and American steel bought western Europe. Or maybe the success of the Manhattan project -- which Stalin was kept briefed on, in detail, by his spies -- gave him pause.
I should add that a very, very large fraction of the Soviet blood that was spilled was done by Russians. Stalin killed maybe 10-15 million before formal hostilities began, including every educated person in the east half of Poland, before 1941. (The Germans killed them in "their" half at the same time.) A large fraction of that number weren't Russian, but maybe more than half were.
You could say that killing 15 million people seems pretty hostile, but that's not how historians count. Anyway the US and Britain weren't evidently bothered by it.
WWII was a slugfest between two totalitarian regimes, Germany and USSR, conducted using troops that were, in the majority, neither Russian nor German, but slaves of one and then the other, and then, typically, executed.
The Western front was a sideshow. Stalin could easily have rolled over all of Europe, but stopped short for reasons known only to him.