I'm not sure if "religion (and spirituality for that matter) weren't especially helpful with those best guesses" in the past. You're right if you say that a lot of religions were often wrong in the past if they made guesses about the physical universe we inhabit, some times they were spot on though in that regard. Fair enough, when religion was right about our material universe it is more likely to have been because they were heavily inspired by the prominent historic (proto-) scientists of the time, and not necessarily through religious-divine revelation. As such, hard science has never been and still isn't most of the major religions forte.

But then again we can learn a lot from religion if we like to learn more about the mind of ancient men and consequently about our own inner psyche and its evolution. Often these are just ancient forms of psychology and philosophy, some of which are still very applicable and relevant today. Those who don't follow dogma can learn a lot about our current inner realities through religion (and legend, and myths, and fairytales etc.)

And then I definitely wouldn't lump religion and spirituality together. While at one point in time they were one and the same, nowadays there has grown a huge divide between those who consider themselves religious and those who consider themselves spiritual but not religious. Spiritual practices like meditation have become mainstream for example, and are because of their proven scientific benefits - which are huge and lifesaving - practiced by people all over the world regardless of their religion or irreligion. I guess in this regard the ancients guessed it right after all.

“Our ancestors worshipped the Sun, and they were not that foolish. It makes sense to revere the Sun and the stars, for we are their children.” -- Carl Sagan