Or maybe ethnicity matters and some diseases impact different ethnicities in different ways?
Different cultures behave differently.
For example, today I saw three elderly Korean ladies, walking down the street arm in arm, like a little wall.
I am not sure that you could PAY an elderly American or British person enough, to stand or walk in such close proximity to another.
Spanish people (Spain) feel comfortable standing 6 inches from you when speaking to you. Anglo-Americans prefer 12 -18 inches.
Finland and Wisconsin (for example) are buried in snow half the year. So people from regions like that entertain at home. So their social habits are indoors, and often blocked by inclement weather.
Most Italians wake up, brush their teeth, make some toast and a strong coffee and hit the streets. They often live with their parents, because of a cultural pattern of inheriting the grandparents flat. But when the grandparents live into their 80's and 90's, people are still living with mom, up to their 30's and 40's and even 50's. So no babies because folks can't or don't want to start their lives up, until they get their own flat.
So lifestyle factors weigh in, a lot, in how disease is transmitted and how a population ages.
Italians are like that from cradle to the grave. Old men get together and drink coffee and play dominoes and shoot the shit, all day. Come home for dinner, etc.
Genes might play a role. But in the case of COVID 19, we don't know really until we have a lot of cases. If Black people simply are not dying from it, even homeless ones in New York, DC and LA then they could have some weird immunity.
They are much more immune to malaria, for example, then we are.