I understand what you are saying. That is why we rely on the Church to filter out the moral and revelatory content from the chaff of the times and mores.

Pointing that out to someone who has already rejected both the Church and its teaching is not a particularly productive approach to discussion.

The primary message from the slaughter of the Canaanites appears to be that the land is a gift from God. We do not know whether they slaughtered everyone - the history of the Samaritans seems to indicate that they normally did not.

The Jews rose morally in degrees, not in an overnight act of the Almighty, as Jesus’ corrections on matters such as divorce illustrated.