Unless you attended vastly different schools then I did then you did learned about the mathematical achievements of other cultures.
You would have learned about Babylonian, Egyptian, Inca mathematics. Learned how the Egyptians know Pythagorean theorem before Pythagoras. How Europeans learned Arab numerals that are really Indian. And in fact would have learned about a number of Muslim scientist and mathematicians who worked in the 9th-13th centuries.
However you do forget the biggest difference. When Seki Takakazu discovered his thing, Japan was sitting on its hands, closed in.
When Newton discovered his things they were known to every European country (and in fact every continent) within a decade. World wide expeditions had been set up to make astronomical observations to prove his theory.
It is not enough to discover a knowledge. You have to spread the knowledge.
“ most people in North America don’t know who he is”
Most people dont know any mathematicians. White or otherwise. If they want fame they should attend the American Idol instead of doing mathematics.