That is interesting, but I have two thoughts:
1. Africa shouldn't be congratulating themselves yet. This isn't over (look at India - they were slow to take off but now their numbers are crazy).
2. The age structure / demographics in Africa may explain most of the difference in death toll. Regardless of political correctness, Africa still remains a place where people just don't live that long. See the population pyramid:
View attachment 18865
Compare this to the US:
There are simply more old people in the US than there are in Africa. From that alone, we should expect a higher death rate in the US compared to Africa. The so-far lower death rates in India may also be attributed to this, to a great extent: