Considering that the United States is of a predominantly immigrant ancestry, it is hard to find dishes that don't in someway resemble something from the old world. Even things like grits, which are of a Native American origin, gets dismissed as "oh that's just polenta." Cornbread is just a European quick bread, but with corn. Biscuits are just scones. Hollandaise sauce, while being a mother sauce of French cuisine, is Dutch. Pizza isn't Italian. It's Greek.
Food is a dynamic thing. Europe shares many similar dishes with different names. Boeuf Bourguignon is just a stew, which is just a method for cooking tough cuts of meat that's been around forever. Europe had the advantage of housing several different cultures within a fairly close proximity, even by Mideval standards. Many dishes that "originated" from one country, are really just a version of something that has always been done, but with a twist. Cook a tough cut of meat the way it has always been done, but add a bit of wine and it's an original dish. I'm not saying it's not an original dish, I'm saying that it doesn't get the same criticism as American dishes. Even Mexican food doesn't get the same criticism, and it's based off Spanish and Native cuisines. But American BBQ isn't original because the Koreans are also known for BBQ? Do you see how unfair that is to us? Our BBQ isn't even based off their BBQ.
You say America isn't renowned for good food because our food is often variations of existing food (much like what has been done in all of European history). I'm saying that America isn't renowned for good food, because our distance from Europe didn't allow it. The food you know is fast food (all of your examples are fast food). This is what spread, because gigantic corporations had the capital to spread. So, what happens when Europeans travel to America? They eat some of the worst shit we have to offer, instead of our best. It's the same with our beer. The beer we are known for is piss water macro brews. What isn't known is that the US creates some of the most unique and, dare I say, best beers in the world. Our brewing industry is gigantic and it isn't held back by centuries old regulations on what constitutes beer.
I suppose in all this rambling my point is this. If you come to the US do some research beforehand and eat at a regional restaurant. There you'll find American cuisine, not at McDonalds, or Pizza Hut.