>The reality was a lot less glorious than that.

Yes in reality a lot of people died to end slavery too. The founding fathers were great men and some of them having slaves at a time when that was very common does not really change my opinion of them.

>We don't only hear that angle, it's trivially easy to access balanced and detailed history. Maybe you're spending your time arguing with zealots on social media but the rest of us can actually educate ourselves

I haven't heard a balanced account of history from any mainstream source. I often see school teachers on social media admitting that they believe these radical narratives. So I am compelled to argue with zealots. Lots of people want to believe that there's some "big reason" they didn't get ahead in life, and what better reason than "systemic racism" going back "hundreds of years"? I actually hate arguing with people about this issue but nobody saying anything against that extreme misrepresentation of things can lead to bigger problems in society.

>In fairness those societies were also responsible in the first place for the expansion of slavery into an unprecedentedly vast system

That is not an inherent characteristic of those societies. They just happened to have ships that could cross oceans.

>Can we just accept that, and not feel so defensive?

I'll stop being defensive when people stop attacking me and my society for things that a tiny fraction of people living hundreds of years ago benefited from. The media is constantly trying to stir up racist sentiments against white people under the pretense of talking about history or some other innocuous thing, and it's disgusting. But their goal is to cause conflict, not to actually fix race relations. I've seen race relations in general decline for at least 10 years because of this.