LH, we seem to be agreeing here.
Population density and ecology are the factors here. The potential is visible but the climate to foster major city structures (which in turn foster megalomaniacs and religious empires, which in turn foster the sort of incredible tourist attractions you're thinking about) didn't come together as frequently. We could make the same comparison about the New York metro area and North Dakota.
TRAC: POPULATION DENSITY AND ECOLOGY. What are you not getting here?
Yeah I only gave two examples but I'm not going to flood the entire post with 80 pictures that take ten minutes to load. Those are just solid examples. If you want more Google it yourself.
That's not a "basic" structure, nor is it made of mud. It's hewn from the same red stone that surrounds it and displays a solid understanding of geometric structure. Now Stonehenge, that was primitive.
The mask displays a high level of craftsmanship and an understanding of pattern, likeness and aesthetic.
Together these things indicate high level cognition and development of craftsmanship disproving Duirward's "inferior human" statement QED. I alos disproved the "never learnt (sic) how to grow crops, barely invented tools" bullshit. There was clearly iron and agriculture in many African societies.
If all you see is half naked people in grass huts then all you're looking at is the most remote Central African tribes in the savanna. If I only looked at America's Appalachian dirt holes I could say America was comprised mostly of dirty, toothless people in tin roof shacks and old trailers that would be too pathetic to be on the Jerry Springer show. Of course that would be innacurate since I'd be confusing "a part of America" with "America".
Now I ask you. What is a substantial contribution to human civilization? Take the greatest artwork of the western world. Michaelangelo's David, The Mona Lisa, whatever you want. Did any single piece of art bring anything substantial to human civilization? Did any one building bring anything substantial to human civilization? Would human culture be that different if there was one less Greek Temple of if Rembrandt skipped a self portrait? Probably not, so let's play by your rules: No single building or piece of art made by Europeans or Asians counts as none of them have brought anything substantial to civilization.
What is a major contribution?
If you're going solely by technology then you have a point. There's not much cutting edge, but on the other hand they've never trailed more than a century or two behind the curve either. Hardly an argument for black inferiority if you look at the constantly shifting map of technological disparity throughout the ages.
Art? Well artistically the African influence has been exceptional. African cloth designs were traded extensively in the days of exploration. African sculpture was a great influence on abstract art (Picasso loved the stuff). Most musical styles developed in America between 1800 and 1950 have at least subtle influence from the music brought over by the slave trade.
Changing the course of history? What, exactly does that mean? By and large that means conquering people. Continent A heads to continent B and crushes civilization C. I guess you have point there. Africa never had a grand unifying conquerer and thus never made it to the sort of Alexander/Ghengis Khan/Napolean level of intercontinental bloodbath that would get notice in your book.
So... what was your point?