I think we do know, quite specifically actually. Well, some people understand it very well, but I believe modern science and physics has led most of us to look at this through the incorrect lens of atomism, using completely made up concepts like virtual photons which are nothing more than math equations, light 'travelling' which is the wrong interpretation of what we observe, and general concepts that are so complicated but never really explain anything in a satisfactory way. Feynman couldn't explain what magnetism is, because I don't think he actually knew. Physicists have a hard time even defining what a field is, and the many dead ends that we reach can be explained using things we already knew a long time ago, but for one reason or another, these things were discarded.
The people who really understood electrical field theory never denied the aether, they embraced it, and that is where I think it all comes together in a very 'beautiful' way.
I'm not claiming to completely understand it all yet, but the alternative explanations make a lot more sense to me, which is why I have become fascinated with the subject. I think it's a topic that has to be revisited again and again, as with anything worthwhile in this life, in order to begin to fully grasp it due to the language used, as well as the metaphysics attached to it. As I often share, here is a series from Ken Wheeler that goes deep into it.
https://youtu.be/HkZKrwULQPc