I don't think his various ancestries are of any significance.
I think the poster who spoke of his ancestry was responding to the poster who said "apparently his parents were French/Italian so it's considered ok." His parents were born in the US so they were not French or Italian. They had that ancestry. He also has New Orleans Creole ancestry.
And also his various ancestries may not have any significance in the countries from which is family originated in Europe and Africa, but I can assure you that they have significance to many Americans.
He is obviously a global figure who has spent a significant part of his life outside the US. I think his choice not to speak any words in English during his first appearance underlined that. But when he opened his homily the next day in English and displayed a mild Chicago accent, it actually seemed a bit jarring at first, but it really brought home to Americans that he is a Midwesterner after all, hailing from the region we call the "heartland." It will be interesting to see how that plays out during his papacy.