I tend to rankle when people compare the colonialism of the last few centuries with the pre-capitalist expansion and settlement of ancient societies. It seems like there's a lot of daylight between the English founding Jamestown and ancient Ionians founding Massalia or w/e.
But what do Hexbear's historians think? Is it fundamentally the same social phenomenon across time or is capitalist settler-colonialism its own unique thing?
It sounds like what's actually bugging you is the assumption that anything the ancients did was fine.
It's perfectly plausible that the ancient Mediterranean colonies were just as brutal as age of sail European colonies, but the voices of the victims were lost to pre-history.