I think what irks me about colonialism from like the 1700s to 1960s is how there's a hypocritical cognitive dissonance and that's annoying. What libs did from the 1960s onwards was just removing this confusion by saying that "yeah colonialism is always evil and you should never invade others (unless in self-defense maybe)." Meanwhile ancient and medieval colonialism, whether or not they tried to convert natives and brutally destroy their religions for Jesus, was shamelessly aggressive and predatory really without much cognitive dissonance (it was either vae victus exploitation or a concoction of legalistic jargon). The way Enlightenment-era Europeans up to the 1900s justified colonialism, in comparison, just seems unsustainable because it's plagued with too many weird contradictions.

Most "Westerners" didn't know about or give a shit about Classical Civilization (Anglos, Germans, etc - Italian, Gauls, Spaniards, yes obviously) before their ancestors were compelled by force or persuasion to accept Christianity which connected them to the outside world and historiography. Even then it took them another 1,000 years before they started caring about Classical Civilization outside of their strict Christian framework (and when the Renaissance first emerged it was very slow to spread elsewhere - in large part because it was explicitly driven by Italian chauvinism - Petrarch saw the Germanics as something like a rampaging savage Russian horde - and VGHing over their ancient glory).