I guess I don't object too greatly to this. But there are three adjustments I'd make. The situation in the earlier segments of the Bible is not so much error in the Bible as the fact that there are things that God hadn't revealed yet. Of course they may be errors on the part of the people at the time. I do not accept the concept that sin is simply misunderstanding.
People do often know what is right and choose to do something else.
But this dicussion isn't about sin. It's about apparent changes in God's instructions to humans. I see periods of time sometimes measured in centuries when serious regression took place. Nor do I automatically prefer ideas because they are new. However I do see a general trend if you look over the centuries that we understand things about God's will for us that we didn't understand before.