The physics of lift and aerodynamics were faaaaar from well understood at the time of the first airplanes, though. New areas tend to run a bit ahead of the underlying science; the fundamentals expand to support and improve the applications over time.
but we did have quite a few advances at the time of the first airplane, for example by that time steam & combustion engines were already invented, which required non-trivial understanding of physics, chemistry and material science was very advanced.
I hold a pessimistic view that we are still in hunter-gatherer mode as it comes to understanding cognition.
Well, it's your right to be a pessimist... I tend to think that the current hardware specialized for fast, parallelized linear algebra is at least as good as the wheels available at the start of the industrial revolution, though. We have learning algorithms that can match human/animal performance in a wide - but still constrained - set of tasks, which previous non-learned algorithms hadn't been able to crack. It's a start!
At some point you have to strike rocks to make fire, because the butane lighter hasn't been invented yet. You make do with what's available, and progressively get better at it. I tend to think that we're a couple-few perspective shifts away from getting it 'right,' and that the hardware side likely barely matters. But, I'm an optimist.
People build things without understanding the underlying principles all the time, e.g. the steam engine. You could probably make the case that building things has helped our understanding more than our understanding has helped us build things.
Having said that, you can certainly improve a design when you better understand the fundamentals (vs intuition + trial & error).
