Central authority seems unavoidable.
I think there's a historical tendency for people to absolve themselves of moral responsibility by accepting 'moral' edicts from on high, as well as cultural pressure to incline people to adopt socially acceptable practices. At the same time, though, there's more than enough evidence of counter-culture movements which have expanded to be adopted into cultural norms, or at least accepted behaviours, that we can presume that it's not a requirement that central authority be present and adhered to.
Where Christianity has the Holy spirit, secular humanism has the Zeitgeist.
Or, depending on your take on things, where Christianity has vocal Christians leveraging the belief of others to co-erce/indoctrinate them into accepting defined tenets (and there's plenty of history of rebellion against various creeds, not just in Christianity but religion in general), secular humanism has no defined set of moral tenets, but individual secular humanists still have social norms to navigate.
People still take the edicts of the central authority of society.
Some, certainly, but at every stage of history there have been heretics, rebels, outsiders and freethinkers who have pushed back against the norms, asking the question 'why?' If this were not the case we'd still have slavery, women would not have rights, homosexuality would still be proscribed...
I know some people think this is a consensus of freethinkers but it is still largely tribal and tribes have their ruling classes and opinion formers. Dawkins criticised the tribal only to form one of his own.
Professor Dawkins didn't 'form' a tribe - he laid out a message, and some people chose to adopt that. They formed a tribe around his ideas, he didn't set out to inculcate a group of followers.
Interestingly I was reminded the other day of CS Lewis on Roman Catholicism and why he couldn't go over to Rome ''Not only do you have to believe all they say, but you have to believe everything they are going to say.''
Given Yahweh's history of catastrophic resets of the rules, I'd suggest that's a potential outcome for any Christian, no?
O.