I think you may be coming at this from two errant perspectives, the first being that humanity’s natural state is the assumption of a deity, and the second is atheists’ lack of belief in a greater moral authority, to use your term, is their defining characteristic.
I would say, without indoctrination, the natural state is to not create a deity, than to create one. I would also say, if they were not born to it, a significant number of atheists didn’t come to their lack of faith lightly. Members of my immediate family are all religious to one extent or another. It took years and a lot of internal searching for me to come to the place where I could admit to myself that atheism is the term that applied to me, so yes, a lot of introspection. I wasn’t trying not to believe although, in actuality, I never believed.
There was no need for me to abide with a mental construct of an omni intelligence I could not detect in any way simply because others, who had no more insight than I did, said so. The only moral authority I needed, or even wanted, were my parents, and it had been decades since even that was the case.
I am an atheist, but I don’t define myself by it. I am a son, a brother, a husband, a business owner, a decent recreational guitar player, an avid reader, and many, many other things, the least important and impactful to my life of which is my atheism, which only comes up, to be completely frank, when I visit this board.