You are correct with my positions. About a) we are not necessarily in disagreement, we just probably talk about different aspects of morality. I am personally

You are correct with my positions. About a) we are not necessarily in disagreement, we just probably talk about different aspects of morality. I am personally not a believer of objective morality but find that the closest we can get to is that "mankind's morality", which can be argued to be at the root of collective decisions like laws and judgements. You are talking about individual morality, a related but different thing and indeed, collective morality spawns from individual morality so it is unlikely to give insights about individual morality's origin.