About Pangea... A few things you mentioned were a little off to me...
First you mentioned Native Americans...
I hope you don't mind it, but the reason partly that there were Native Americans was because of the Americas geography. Geography is also what made it logical for Europe and Asia to have developed first. Also there are a few possible suggestions of African influence. If you would like I can expand on this.
Also you mentioned Columbus finding America. He was not the first man to have discovered America. The vikings were and also even if Columbus did not exist there are other indications of Europeans discovering America like Portugals accidental discovery of Brasil which was possible when one of the Portugese strayed of course on thier way to Africa.
Next you mentioned the colonization of Africa. Africa had been involved with the Islamic kingdom before on its own accord. When the crusades had been in effect and invasions were made in the Islam causing an increase in knowledge leading to the renaissance. Maps were something important the west obtained from Islam and they included the knowledge of Africa of which western europe had neither made colonies or new much about. It also spurred interest in sailing to India which also led to some colonization of Africa. Once I again the geography helped in playing its part.
Next you mentioned Africas supply of gems. Yes they could have been used to thier advantage, however, the major African Kingdoms became Islamic and spreaded thier wealth to the Islamic Kingdom via the pilgrimage to Mecca. This is probably another point that led to the colonization of Africa which once again was put in place by the Geography.
Don't worry I'll talk to you a bit more about Geography and its important role. BTW how much do you know about world religons? I personally know quite a bit because most of the relatives on my dads side were Buddhist and so I became interested in learning about other religons like Buddhism which originated in India.
I really don't like pointing out flaws, but I would eventually have to. Feel free to make any arguments to defend yourself

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