When I was studying for my bachelors degree in engineering, the Asian and Jewish students kicked my rear end. They would score 90s on Thermodynamics and Heat Transfer exams, and I would barely get a "C" even with the test graded on a curve.
In middle and high school, the backwardness of Africa was always explained as being the fault of "European Colonialism." This was an abject lie. It is a solid fact that those nations that accepted colonialism to a greater degree are better off even today than those who did not.
My personal opinion is that the Jewish people (who definitely are a race) possess the highest intelligence. At something like 0.2% of the world's population, they have won over 25% of all Nobel Prizes in Economics, Medicine, Chemistry, and Physics.
Every nation that has had a large Jewish population throughout history has partially thrived because of them, and every nation that persecuted and kicked them out has suffered.
And yet book brilliance does not equate to practical use.
Give me a less intelligent person who can actually DO something with what they know over a rocket scientist who can't remember where he parked his car.
"In your seed all the nations of the earth shall be blessed, because you have obeyed My voice." Genesis 22:18
While the primary blessing is referred to here is the coming Messiah, Jesus Christ, the Savoir of the World, I believe it also includes the blessings attached to the Jewish people and the treatment of them by individuals and nations.
"I will bless those who bless you, and whoever curses you I will curse; and all peoples on earth will be blessed through you." Genesis 12:3
I think some of it comes from the belief that intelligence is a pure skill that can be developed like any other skill, given proper instruction and nurturing.
I see many inherited traits that leave me in awe, and I know I have no more ability in mastering them than in becoming an Olympic champion (athletic ability is also inherited, and not evenly divided among the races).
To quote Harry Callihan, “A man has to know his limitations”. He also needs to recognize his strengths and concentrate on those.
As for your last paragraph, I think it has more to do with Genesis 12:3.
Jews have had a particularly bad time of it historically, and probably the more stupid ones have failed to survive, while the smart ones did. Africa had major towns and cities, but the people who were captured and sold as slaves were often taken from the forest and undeveloped areas. It is likely that the more enterprising even in those days might have gravitated to the cities or escaped into the forest. Thus those brought to the Americas may have not been the most intelligent. Survival in slavery was not usually a product of intelligence, but of physical strength and obedience to orders. Culturally, of course, Jews, Orientals and other Asians place a strong emphasis on education and diligent study. Also, it was not easy for these populations to flourish in this country decades ago.