It is also noteworthy that the U.S. lost approximately 500,000 troops, roughly a third less than the Civil War. The Soviets lost 20,000,000.
Their first tanks had 300+parts, a year later they were down to 180+ parts, to get them out, with much less protection.
No, they didn’t win single handedly but they put up a wall of people, who were slaughtered, so that others could actually help them win.