I'm not downplaying the importance of the Russians,
You are in fact . As you sumps up the war to the US troops which arrived 4 years later everybody in Europe....... It is easy to make bomb, tanks and training of soldiers for 4 years when other are fighting 6000km away and arrived to finish the work against an injured enemy like Germany. And even when they arrived, US were not alone to fight, French, UK, Serbians, Russians, who started 4 years later, were still going on fighting.... The only Nations which really could give lessons for WW2 = UK, Russia and Serbia.