Americans think the way they do about WW2 for the same reasons you would say what you said right there. Its simple, every country has its own propoganda, we (United States) are tought that our country is the best and no one could stop us no matter what happens, we down play our failures and up play our achievments... as im sure Russians do the same, and Germans, and Egyptians, and Swedes, and so on... im sure if you ask a Franch man about WW2 they will tell you the resistence was one of the most important parts of the allied victory, not saying it isnt, it very well could be, its just the point of view... "our country is better than yours" we are all tought that, and id hate to see the world if we wernt
however that being said, the very few that you can get to actually talk about history or understand it for that matter here in the States would clearly state that we by no means did it on our own