I think you're engaging in what I've heard called "the historian's fallacy"--kind of "Monday morning quarterbacking" and assuming people in the past had access to equivalent information and I guess perspectives and analogies and experiences as you.

I get heavily down downvoted and my posts removed on rAskPhilosophy because quite honestly I don't think I'm really doing philosophy--I'm much more interested in things like psychology, history, maybe a little political science and economics, BUT there exists something called "the curse of knowledge" where once you know something it can be very difficult to understand what it's like for someone who doesn't. We live in a very diverse, generally scientific, information-rich environment where it's very easy to see what good it does to be nimble and flexible and say, "I'd prefer to do it THIS way, but I can see where you're coming from if you want to do it THAT way, THAT way, THAT way, THAT way or THAT way." e.g. The Crusaders didn't know a God-damned thing about Islam because they didn't have relationships with them such that they could have a lot of translators and even if they could, they'd have to write down what they were saying and it was very difficult to make many books, so they'd kind of have to decide between learning about Islam or learning about Christianity. And they didn't live in a highly scientific environment where they felt like they had a good handle on how things were going to go--they literally saw God working on the world in their day to day lives when so much happened that they couldn't explain--all they could do to give themselves any sense that they could make any productive effort in the world and they shouldn't give up and just kill themselves to end their suffering was say "don't piss God off." This was before Modernism and existentialism and things--they didn't think "I should create my own meaning or at least select the one that best represents me from multiple available, viable possibilities," they thought "I must submit myself to the one, true God and the essence of wisdom, all else is folly and ruin."

And as I'm saying as time went on and other possibilities became apparent, it depends on what you think counts as evidence. People who it's sometimes productive to call my enemies, conservatives and traditionalists, basically, explicitly say things like "the concentration of wealth in the hands of a few has always caused society to survive and progress before," and I don't think they're explicitly, intentionally lying, I think they honestly believe it.

I'm on my phone and this is getting long, but I think that's the gist of it.

EDIT: PS I just thought of the example of I think it was Semmelweis and germ theory: he had scientifically come up with the idea of "corpse particles" that were being transferred between autopsies and childbirth, making the mothers sick and killing them. He tried to communicate this to other doctors, but supposedly one of the reasons this didn't take was they didn't believe that they, engaged in a learned, gentlemanly pursuit, could get dirty and need to cleanse themselves. They didn't say, "Oh, I see where you're coming from and these corpse particles I'm sullied with are killing people, but I think it just makes me look bad and is bad for the profession, so I just completely of my own free will with my entirely informed consent just elect to put my fingers in my ears and act like it's not true"--it went against everything they ever "knew" about what was morally and factually right, so they honestly didn't believe it.

EDIT 2: PPS They had had some success predicting and explaining things with miasma theory, e.g. designing hospitals for airflow. "The truth," such that germ theory is the truth, isn't simple and natural and obvious from all perspectives in all experiences.