OK, so Galileo wasn't omniscient. Big deal.
The phenomena of the universe are never going to be 100% comprehensible by the human brain, because the human brain is not able to cope with the required amount of complexity. The universe will always be partially ineffable to us. Our brain is only a small lump of electrified fat that evolved on the plains of the Serengeti to be good at a few things:
* identify visual patterns, in particular:
- human/primate faces
- predators with big teeth
- food
* judging how easy/hard it will be to leap to the nearest tree branch
* socially interact with other members of the troop/family/tribe, including:
- language,

and not much else.

It's a fluke that these brains grew so much in response to those things that it is also accidentally able to invent and appreciate art, mathematics and science.

But, that fluke isn't so infinite that it will enable us to comprehend all of the phenomena of the universe. But that's OK, we can still be immensely powerful, we just need to trust that our mathematics' conclusions can be trusted. Take, for instance, the dual wave-particle nature of light - our brains are literally incapable of "fitting" such a concept inside our minds. We can visualise and understand a wave, we can visualise and understand a particle, but we cannot visualise and understand something that is BOTH. So we build mathematics that "works" with that thing that is both - and 'poof' it works, so now we can effectively understand it, but only by using and trusting the mathematics. Our understanding of light exists "outside" of our brains - it is partially detached from our brains - it exists on the paper of the pages of the textbook and there it must stay, because our primate lump of electric fat simply cannot grasp the concept of what light actually is.