The funny thing about this (although a joke), is that the U.S. played a very very small role in WWII. At least on the German side of things. Before D-Day had ever happened the Russians had overcome the Germans in every way. They had completely pushed them back out of their country and were pushing towards Berlin. Germany was run thin and expending most of its troops to fight on the Eastern front.
So when D-Day came around, the British and Americans troops weren’t encountering that much. Had the Russians not succeeded and the British and American forces launched that attack, they would have been absolutely obliterated. German technology was on par if not better than that of the Americans and British. Although, it didn’t help that the Germans guessed wrong on where they would attack, for the most part German military strategy was better as well.
Of course it doesn’t look that great in propaganda when you go around saying that D-Day didn’t mean much and really only a rubbing salt in the wound that the Russians had created. So of course they explode it to as the American saviors of the war. But in reality, the Russians are what really brought around the biggest turning point into ending WW2 in Europe. Americans/British helped, but not to the extent that the propaganda would have you believe.
The U.S. nowadays, is indeed still a superpower and the largest power in the world. However, they are no longer the power they were after the end of WW2. The economic gains and strengthening in China, Japan, and the rest of Europe has made the U.S.'s a little less dominant. Not to mention, since the Reagan years, the perception of Americans around the world has vastly dropped into something more of a country like Nazi Germany, USSR, etc. One that uses their power purely for their own gains. And during the superpower years the atrocities committed in Africa, Middle East, and South America have pretty much set the course for it’s own demise in perception and credibility nowadays as you are seeing. Things such as funding revolutions in Centra/South America and Africa which have led to the political problems there. POlitical problems that have led to opposing American regimes such as the one in Venezuela. Or Middle East where the Americans funded, armed, and supported the revolutionary groups in Afghanistan when the USSR invaded... those that later branched off into the radical Islamic groups that have been deemed “public enemy #1” nowadays. The list goes on and on which slowly starts to show the demise of American dominance in the world.