I know it didn't change anything for those who were enslaved, but it may also be good to remember that it was a time when all major powers used slaves, and France made a point of never allowing it in the actual country.
Slavery absolutely existed in mainland France under the Romans. The coronation of Charlemagne made the popes feel empowered to order Christians to stop enslaving other Christians or selling the latter outside Europe. Believe it or not, Venetian slave traders used to kidnap civilians in Rome and sell them to the Arabs. The growing influence of the papacy lead to the gradual replacement of chattel slavery by serfdom around the tenth century. Finally, in 1315, bonded labor was abolished in France by Louis X, proclaiming that "France means freedom".
A similar process transpired in England, with slavery abolished by William the Conqueror and serfdom dying out in the fifteenth century as courts refused to enforce the contracts.
Unfortunately, all of this brilliant progress was undone in a desperate Europe facing a massive Ottoman invasion at the dawn of American colonization which led Popes and Emperors to authorize horrific measures, that ultimately corrupted the European conscience and led to a new era of slavery and genocide.
The Ottomans cannot carry all the blame, but remembering that "we" (qua the West) built our system of racism from a position of weakness may help persuade some people to let it go away. I think. Who knows?
This is really key here. There's a trend to hold people of the past up to standards of the present, but the world was extremely different then. Before the advent of farming machines and nitrogen fixation, labor dictated the power of a nation, labor relations and unions weren't a big thing, and a huge majority of the population worked in agriculture. Because there were no nuclear weapons capable of destroying the entire planet, superpowers commonly fought for resources, meaning the surviving nations had to be strong. The world is different.
That is not a question of change within centuries, that is various people at that time making active decision to keep or abolish slavery.
Napoleon contemporaries did characterized him as power hungry tyrant. This is not just projecting current values. People in the past had opinions too.
There's a trend of assuming that people in the past were simple, without agency and that society was uniform. Contemporary people do make own decisions, some of them harmful and egoistic. We don't blame current political decisions (including stuff like what Isis did) purely on circumstances. The past people deserve the same treatment.
People who study politics absolutely use circumstances to explain political outcomes. Historians discuss the economic impacts of WW1 when talking about the rise of Hitler and Nazi Germany. People discuss the complex political history of the middle east and its long history of resisting superpowers combined with the power vacuum when the US left the region when discussing the rise of ISIS. Power vacuums and food/water scarcity are often the root cause of political instability.
Crazy individuals do crazy things, but those crazy individuals gaining power is always a result of the political system in place at the time.
The discuss it a little. The books I have read about rise of Hitler did not blamed "economic impacts of WW1" all that much. That was far from being a single or primary thing.
The choices, values and opinions of major actors plays huge relo.
Slavery was wrong then and it is wrong now. societal consensus cannot be excused because it was in the past.
Highlighted and rightfully acknowledged but slavery cannot be simplified to just forced labour when rape, murder and unethical experimentation was also performed. I think it’s incorrect to assume that this should not be criticised with the standards of today as to do so is to ignore that it is a very human issue to value the life of another so poorly and assume we were all barbarians only 300-400 years ago which is not the case.