There haven't been extremely many presidential elections.....so it's not statistically probable that every demographic group is represented. Why has there never been a Native American President.....or a German American President?
Who even cares?
Eisenhower was German-American
Hoover, FDR, and Truman were part German, too.
It is significant that as late as 1960 America had not even had a Catholic President even though Irish Catholics were a large part of the electorate and had shown much success in large-city and state politics. If Irish-Americans could not win the Presidency, then how could Italian-Americans or Polish-Americans?
Presidential campaigns succeed because nominees are able to consolidate support in several regions of the country and win a couple of swing states. Such well explains the absence of random-scatter Presidential elections in our history.
We do not have a random scatter of Americans by ethnic origin. Patterns of immigration concentrated Italian-Americans (and others of the late-19th/early 20th century wave of immigrants) in relatively-few areas. Italian-Americans settled heavily in a triangle from Boston in the northeast, Norfolk in the southeast, and Chicago in the west, and along the West Coast where there were opportunities. The pattern also holds true among Polish-Americans, "Russian" Jews, and Greek-Americans.
Until 2008 political realities were such that politicians unable to win the very rural parts of America with white populations descended almost exclusively of Protestants with origins in Great Britain and Northern Ireland just could not win the Presidency. Barack Obama shattered that reality, so we may have just seen the end of WASP dominance in Presidential elections.