You've just contradicted yourself. If we could understand nature at a fundamental level, then it's not an assumption at all of course it's incorrect. I'm looking at the probability of it and its a very good assumption. If God has not designed the universe in a way that we would eventually be able to imagine it completely, and if we have not evolved brains to imagine such things which do not increase our fitness, why do you think it is more probable that we will ever be able to imagine what lies behind the maths of quantum physics and the rest of it? To me it sounds a bit religious.