>>18064819old testement, the torah at least, is just basic rules like cook your food, wash your hands etc. there are guidelines like if your animal causes property damage then you are not at fault unless your animal was known to cause perpty damage then you should pay for it. there is an intelligence to it that we take for granted, like God makes the priests wear pants around him. In the gospels Jesus calls out the corrupt pharrisees and helps explain how you should behave in general. things are more abstract. like at this point people assumed rich people were rich because they are blessed by God, but Jesus corrects them and radically says all that matters is in your heart and no one is passed redemption.
Imagine trying to civilaze a non christian society like india or china, how owuld you convince them to not shit in the street or cook food in sewage? it would be easiest to tell them they will be morally unclean if they did these things. then once society adapts to this in a few genrations, you can start to bring in the more abstract, high iq teachings of Jesus. I honestly think its about time for another round of divine teachings because of how radically different society is, we need help to figure otu how to live with technology and modern horrors