A tiny comment about this:
We surely cannot grasp the concept of an infinite universe. Consider this. We make theories about how earth was formed. How our solar system came to be. How the life began on earth. Can anyone ever make a judgement about how the galaxies came to be? The stars, the planets, they're all made of some matter. Can anyone ever explain how that matter came into existance? No.
The only thing we are really cluless about is the nature of life. We know how galaxies are formed. And galaxy clusters. And super clusters, aka "cosmic strings".
The build up of matter is known. (nucleosynthesis) Light can turn into matter (and anti-matter) in a process called pair production. Matter is not quite as solid as we think. It consists of mostly empty space. You have never tuched your keyboard, or anything else for that matter. The macroscopic world we live in has only 2 fundamental forces, gravity and the electrical force. Gravity keeps us on the ground and makes galaxies etc, all else is due to the electrical force. Colour. Taste. Light. Solidity. Opacity. Structure. How something feel. Is it smooth or rough? You never touch it. You only feel the electrical force between your fingers and the object.
I would say there is nothing unexplainable with the natural world. Althoug a lot of the explanations are still hidden from us, there is no reason to think it impossible to find them.
How the human mind works, however, now that is a mystery. :)