How do you find meaning as an atheist?

[Brian37]

Our species flaw is that we did not evolve to question the gaps we fill in because of our ability to have flawed perceptions.

The upside is that we do have the ability to question, but most of the time gap filling is our intellectually lazy way out.

I would disagree a little. I think a significant part of our evolution is that we evolved to be part of a troop of animals and therefore it was useful that different members of the pack think in different ways. One approach is not intrinsically better than another, and what worked well solving the last problem, might not work as well for the next.
Until we have all the answers we have to fill in parts. to make use of the knowledge as a group.
The problem with the goddidit mob is they do not want to recognise parts of what they thought they knew, were just bits that had to be filled in at the time to make a sensible proposition, and now that we know better we can reconnect our knowledge with a better tested proposition.

I am not sure we are saying different things.

Placebos do work in creating groups which make survival a better chance, but it does not make the placebo real.

"The God Delusion" by Richard Dawkins discribes this flaw as the "Moth mistaking the light bulb for moonlight".

He also describes the reaction to the questioning a social norm in the form of a placebo, like a subordinate bird offers help to the alpha male and the alpha male reacts violently to that help.

My point and I think his point would be, everything is evolutionary, both our rational and irrational behaviors, and neither are absolutes as to getting to the point of reproduction. It still amounts to variety and crap shoot based on evolutionary biology.

Cant make evolution an "either or". It is the same false analogy that science is either deterministic or chaos. It is both and both overlap and interact.

Just like we can say that a hurricane is a hurricane based on winds speed and shape of a storm. But the QM part of it would be the exact number of raindrops, and to a lesser degree, the path it might take.

Both rational and irrational behaviors exist in humans. But we do not OVER ALL collectively have a working understanding of the natural world and tend to prefer our base tribalism and superstitions over pragmatic use of logic.