I believe every nation should put its own people first and the rest of the world second. Otherwise there is no point in having nations at all. If my fellow countrymen, people I see daily and have a vested interest in helping, were suffering I would be rather upset if money that could have been spent helping them was given to some African nation to build a school. Not because I don’t want the Africans to have a school but because the government is using money it gets from the American people to help other nations as Americans are suffering. We already have organizations like the United Nations and Commonwealth of Independent States who focus on a broader picture. I would prefer if the American government provided for the American people first and focused on the outside world only when the problems plaguing the nation are alleviated.
I think by making America great again, people are talking more about the economic prosperity and unrivaled power America held during the 20th century as @P_Tigras said before. I don’t think Trump supporters are thinking, “Man I wish we could go back to when everything was segregated and women were excluded from certain jobs.” More like, “Hey remember when you could get a job right out of high school and buy a car, a house, provide for two kids, and you didn’t need a college education for everything? That was nice.” I don’t think people want to literally go back to 1950’s America. They just want to bring back the financial security that people of that time period had.