That's only vaguely true for things we've internalized into our own laws. We don't beat slaves because we don't own any. We don't favor the first wife because we have only one wife. The Western ethic or the Judeo Christian ethic if you will has pretty much always said the same things, in context for almost 4000 years. True the mechanics of it have changed but not the intent. For example in the Torah we read in excruciating detail the construction of the temple and the process for ritual sacrifice none of which exists today. But that's not the point, the point is obligation to God and to justice and to ethical principals.
All of those other societies that had temple whores and child killing, mutiliation, humans as gods as humans, degraded family relationships and what we in west would generally consider perverted values are gone, because they were perverted or extreme or whatever you want to call them. So that which is not moral now was in fact not moral then either and it simply took time, warfare and assimilation, depravity and weakness to prove that out. Whereas we Jews are still around. Telling the same ethic.