We certainly are limited as a species. What we each believe is what our limited senses (sight, hearing, etc.) and our earthly experiences have shown us. This is all we have to work with. We view the universe through a piece of clouded quartz and listen through a tin can at the end of a long string.
Our theories are an extention of our imaginations, but are driven and prooven or disprooven by the observable, measurable, phenomenon around us. Children are very imaginative but produce theories which are far from truths. Theories must be grounded in true science.
OK, I don't know how I got here from E=mc*2 and that is the sign that one should abandon a topic for fear of rambling.