I don't think that African Americans are the youngest culture in America but rather one of the oldest, considering the slave ship theory they've been here quite a while. However I strongly agree that they're still very wounded and needing healing.
Further, there's evidence being brought out that there actually were aboriginal Americans that we would call black.
What I mean by age is age of connection to older cultures. Almost all western countries have wealth, either literal or cultural from Greek and Roman civilizations. Asias subcultures have roots in Chinese culture. African American culture was fully severed from the mother culture in Africa so it's age is much younger compared to the thousands of years other cultures have evolved over. One example of a cultural strength, appreciation for education, is often taken for granted. Racism is the idea the blacks have an innate disdain for education but it's actually an ubiquitous cultural strength common to all cultures EXCEPT slave/severed cultures. Affirmative action is unfair from the lens of the present, but it is basically compensation from the lens of history, speeding up development of this basic cultural strength. Affirmative action that doesn't heal this rift annoys me as the compensation is not going to the victims. The vanity metric of black skin is often achieved by pulling from Africa where the ancestral culture links had stayed intact.
Trying to assign 100% of the differences between people(s) to their ancestral cultures is a grossly oversimplified post-modern mythology and unsupported by facts or a contemporary understanding of the science of human populations, and I'm fairly sure many Asians and Asian-Americans would be quite offended by the statement that their ephemeral "roots in Chinese culture" are what lead them excel where others struggle.
Don't be blind. Culture definitely provides tailwinds and headwinds in certain areas. Ignoring your attack on the strawman of 100% explanatory power the actual degree of effect may be very small but compounded over time.
A simple example is being good at multiplication in kindergarten. This small advantage can become a desire for continuous academic excellence via courage towards math. If a child's parents are stereotypically prudish, another "advantage" is the ability to sidestep distractions of athletics/sex.
If the natural momentum a culture can build isn't appreciated, people become shallow and hoarding. In my family for example, the idea that Asians are naturally smarter and Blacks dumber is common and was the impetus for my thoughts in this area. I see a greed and lack of empathy developing that is difficult to watch.
The most common actual real world usage I get out of explaining this model is more support for affirmative action. Perhaps other people can see it as having other value. No need to trash it. All models are simplifications of reality and thus "wrong".
Further, there's evidence being brought out that there actually were aboriginal Americans that we would call black.