You are correct that just because X occurred at times in history, that does not mean X is appropriate for today.
But that is too broad and too vague of an argument.
Take murder, for example. The philosophical, moral, and legal injunctions against the unjustified taking of a human life have always been a standard of a 'civilized' society. This injunction is old and consistent in every culture, and always been the first to be legally enacted before anything else simply because in order to have a cohesive society, every life must be protected.
So in a manner of speaking, you cannot use that overly broad argument. Sorry.