Our brains haven't evolved since we huddled around a campfire, telling stories to ward off the evil spirits.

Because they're either quick or dead.

Quick, do you attribute your atheism to thinking based on scientific evidence?

I think the fast/slow two systems notion by Kahneman applies to all of us. The cognitive miser thing is a matter of not expending too much energy in brainpower. We have gut feels, intuition, shortcuts for good reason. One doesn’t want to spend too much time with physics calculations on acceleration, speed, and what not when confronted by a grizzly bear in the woods. There is paralysis by analysis. And gut feels help break the Buridan ‘s ass dilemma. There are people with deficits in assigning valence to choices because of brain damage to emotional regions of their brain.

It is tougher to make decisions based on reason and evidence, to have the self-regulation to engage in long bouts of deliberation before making a choice or test something more than a reflexive hunch. There are so many fields of knowledge requiring specialization and years of discipline to achieve competence and then expertise. We trust experts and form opinions based on secondary and tertiary sources.

A tad of knowledge is a dangerous thing as competence doesn’t quite match confidence and people think they know more than they actually do (illusion of explanatory depth). Adam Grant explores some of this stuff in his book Think Again. Sadly he gets some stuff wrong on brain evolution referring to the amygdala as part of the “lizard brain”. He also incorporates the Dunning-Kruger effect heavily into his narrative, despite some debunking of this effect as a statistical artefact. So even scientists can voice questionable opinions, though the main point of his book is to not be overconfident about what we assume to be true.

Because we are human and social creatures. AI will not have this problem, unless we want AI to mimic humans which many seem to want and I have never understood eg we have enough humans.
It is a good thing to hold opinion I think eg Scientific evidence may well conclude an ecosystem be radically altered to benefit civilization. My opinion would be the loss of other non-human life that would entail is unacceptable and in the long term, would actually detract from civilization. Science has no emotion in other words so opinion is important. A case of; Just because we can, does that mean we should?
Opinion is one thing but when vigorously pushed it becomes an agenda I think. And I think agenda's are adopted in favour of scientific evidence largely due to repetitive messaging and subtle coercion.

Yes, I think that it is quite correct, that it is in part the avoidance of the effort, required to revise existing ideas, that is in part to blame. Though of course it is well proved by some science that, we are also programed to favor authority, and if we therefore see those who influenced our opinions, in the first place, as having more authority than science or scientists, then that would probably be another supporting reason.

But then, that bit of science was, very strongly favored by Richard Dawkins, the well known and respected scientist and thinker. So I would not like to sound like him, as I know that you are very choosy about which scientists you cherry pick from. And I wonder, does that count as favoring opinion over science ?

Personal growth and changing opinion is very hard. Sadly though I am still waiting for you to explain your theory about achieving personal growth without altering position, that you told me about a few posts ago. That would surely make it easy as well.