To the OP, my suppositions (based on an assumption that the Africa/America/Europe slave trade had never started):
Africa
Not much different to how it is now. Slavery was already going on among African tribes - we just elevated it to an industrial scale.
We'd still have raped the place though. Dutch, Portuguese, Belgian, French, German and of course Brit opportunists were already there for Gold and other valuable ore, Ivory, spices, timber, missionary work. . . Slavery was just a financial bonus.
Europe
The Industrial Revolution (which spawned steam engines and railroads and the subsequent development of the internal combustion engine, mass-production, enhanced mining, metallurgy etc etc) in the 17th and 18th Century were a direct response to the need for faster turnaround of cotton spinning and weaving.
The cotton was Europe's major by-product of slavery.
We'd probably have developed the technology, but without the exacerbation of the cotton market, I guess 100 to 150 years later.
USA
Would the southern cotton industry have been as successful with paid laboUr? I doubt it. So a less prosperous confederacy.
Would there still have been a civil war?
I suspect not.
We could be looking at a 21st century confederacy in what is now USA, with decent odds it would be part of the British Commonwealth like Canada and Australia.
And African Americans?
Without the cultural memory of being systematically repressed and brutalised by a specific demographic, the current understandable bitterness might not be there.
Snoop Dogg would be rapping about growing roses, Michael Jackson would still be a black mentally ill man (instead of being a white mentally ill girl) and Chris Rock's standup Routine would be 1min 12secs.
As it is we've ingrained a mistrust that will probably endure for another 200 years.
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"I started out with nothin' and I still got most of it left" - Seasick Steve