First, the word "possibility" is a perfectly acceptable word in a historic context. Consider, for instance, the following sentence:

Apples and oranges. If you were to use the example sentence as proof that Polynesians reached the new world first, then it would be false. You're using the possibility (not probable, possible) as definitive evidence, which is a "no no".

Second, I would hardly consider an academic article from the Journal of Archaeological Science to be "wild speculation."

Misunderstanding. I was referring to the inexact nature of the discovery of the bow as "wild speculation", as no empirical evidence was presented. Merely the possibility that bow's origins took place at a very improbable time in history.

Regarding crops: Does this mean that the Cherokee are genetically inferior to Mexicans?

Of course not, at least not in a microcosm. The inability to cultivate a particular crop is not, by itself, a sign of genetic inferiority. Since the cultivation of that crop was used as an example of genetic equality/superiority I offered a counter argument.

It is now becoming increasingly apparent that the diffusionist theory [that Nok ironworking comes from North Africa] tends to be simplistic and mostly lacks hard evidence to support it.

Language. An idea "becoming increasingly apparent" can simply mean that an idea that had no following whatsoever now enjoys a slight following. Judging by the language it's clear (to me) that "diffusionist" theory enjoys much wider support, but is not the only theory. The bolded text above comes from the alternate theory which I believe (from the context of the document) doesn't enjoy even moderate popularity. I acknowledge that a theory other than "diffusion" exists, I just don't believe that the paper finds is as credible.

To figure out who the cherry picker is, why not just quote the whole paragraph?

I'm trying to avoid that, but not for reasons of cherry-picking.

But he has an important piece of evidence—Nok pottery, found inside the furnace alongside the charcoal, suggesting that they were placed there around the same time.

Do you believe that the above statement can be used of definitive proof of anything? Could you present that statement to a scientific journal as proof that metallurgy was alive and well in Africa in 1400 BC? Of course not, it's speculation. The science is saying one thing, the speculation is saying another.

Let us not forget what this is about. You presented several examples of proof that Africa was equally or superiorly advance as the rest of the world. I'm simply challenging these examples and pointing out differences between proof and "possibly", "suggesting that", etc.