How to make sense of so many conflicting theories and ideas in the field with an open mind? Is every school of economic thought as valid as the rest?
This is how I view it. At the very core of economics, is each and every human on this earth making decisions he or her thinks are in his or hers best interest. In real life, we do not calculate utility before making a decision or compute any expected values; we do what feels right at the moment.

Taking the cross-section of human decisions, economists try to make sense of it all, and ultimately deduce some theory that resembles a law of physics to shed light some basic insight into the human condition.

This is a mighty hard task; near impossible. Its amazing to me we've made any progress at all, yet here we are.

As a field of knowledge, economics will never explain the world perfectly in whole, because the nature of what we study is far from perfect and certainly stochastic. There will never be a unified theory of economics, but that does not mean the small pieces of insight each economics paper tries to uncover is trash. It is still valuable to use what the data can tell us, to the best of our ability, to guide our future decisions, and analyze the decisions we've made in the past. 

If anything, its interesting as hell.