No solutions here, but variations:
I second the importance of remembering the incredible depredations of King Leopold on the Congo. The book by Hochschild can be found online. It wasn't a true case of colonization, not that this justifies a thing. King Leopold treated the Belgian Congo as his private domain, which he depoiled with no trace of conscience. The story of this despicable treatment of millions of human beings was a cause celebre of its day, the unmasking of it through close attention to rail shipments reads like a detective novel, reminiscent of the "dog who did not bark".

Another book, less historical, but no less memorable, is "Shaka Zulu" by E.A. Ritter. The version that I read took a sympathetic look at Shaka and the Zulus but it told of massive bloodshed by Shaka and his generals who set out to form their own empires at the expense of their neighbors. Genocide is definitely indicated.

Then there are non-European colonizers/ destroyers, such as Genghiz Khan; The Huns, various intra-Chinese warlords, the Tartars, and the Rus who fought the Tartars.

I don't think the Celts and their Druidic elements would have much positive to say about the Romans and Christians who wiped them out in large numbers. I don't think the Babylonians would have much nice to say about the Assyrians (or have I got that the wrong way round?) Nor the Carthaginians the Romans, the Byzantines the Turks, or anyone in the Near East or North Africa the Ottomans (see what I did there?) And try and find a Zoroastran in Iran, now. They're there, but they take some finding. I don't think they shrank voluntarily.

Istanbul was Constantinople
Now it's Istanbul not Constantinople
Why did Constantinople get the works?
That's nobody's business but the Turks!

Does that make what went on in Africa okay? No but Africa's a HYUGE place with a lot of players, and it's not a surprise that a lot of folks got in their business. After all, we all came from there at one time or another, and went to Europe and got in the Neanderthals' business.