[Pollster1]

Pretty good memory. It’s too bad (from the “progressive” perspective) that those three were simply Christians who happened to be black Africans. Their skin color didn’t matter to them or to those who elected them, just their willingness to follow God. Since they were not part of the victim class, today’s journalists don’t think they count.

[Verginius Rufus]

We don't actually know that any of the African popes were black Africans. Two were from North Africa and the third was apparently born in Rome to a family which came from North Africa. There were some black people in the Roman Empire but there is no evidence that any of the African popes was black.

There have been cardinals from black Africa for decades, well before the ones who are currently in the conclave, but I wouldn't expect Bob Schieffer or the other two to know about that.