You want to refer to Brazilians, Mexican, Canadians and Guatemalans as 'Americans', knock yourself out. But these are continents, not nationalities. You want to mimick the 'French' and 'Germans' as being 'European', then you'll need to refer to Mexicans, Americans and Canadians as 'North Americans', not 'Americans' to be consistent.
Hondurans and Brazilians are Central and South Americans, not 'Americans', which is too broad a term. Regardless, you can call them anything you like. It is a free country, but nothing you call them will make them citizens or people of the United States.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.