Those few hundred man had firearms. Those black people would not have had anything but comparable weapons.
I don't think it is safe to presume that there are enough indications to presume that those Olmec statues portray black people. I know that they look a bit like black people, but sometimes people have a strange way of sculpting.
Historical Review: Megadrought And Megadeath In 16th Century Mexico (Hemorraghic Fever)
"The epidemic of cocoliztli from1545 to 1548 killed an estimated 5 million to 15 million people, or up to 80% of the native population of Mexico (Figure 1). In absolute and relative terms the 1545 epidemic was one of the worst demographic catastrophes in human history, approaching even the Black Death of bubonic plague, which killed approximately 25 million in western Europe from 1347 to 1351 or about 50% of the regional population."
"The cocoliztli epidemic from 1576 to 1578 cocoliztli epidemic killed an additional 2 to 2.5 million people, or about 50% of the remaining native population."