The Romans viewed the Colosseum as the zenith of civilisation, representing the natural order playing out in glory of the Gods. In the arena was unadulterated murder and torture for the entertainment of the baying crowds.
People 2,000 years ago are us, just brought up differently with different beliefs and living under different conditions.
Humanity has mostly now progressed enough to recognise the depraved evils that were socially accepted in previous times; yet a person of the time would have gone along with the accepted norm, assuming it was right because everyone else said it was right. They were wrong.
Unless you think we are currently at the zenith of civilisation, what are the great injustices of our time that are socially conditioned and accepted? These wrongs will have been justified and reasoned away to become the mainstream behaviour.