These are very long-standing principles of Jewish law, that long precede Jesus. I think that what is meant by them is that without for filling those two precepts, it is impossible to fulfill the law. However, they alone are not sufficient. There are many other laws that need to be followed to be the best person that you can possibly be. God does not expect any of us to be perfect, but He does expect us to strive toward perfection, with all of the handicaps of our intellectual and spiritual imperfection. This involves studying the law and all of its implications in the society when and where we live, so that we can properly strive toward perfection through our actions.
“for filling” should be “fulfilling “
“Teacher, which is the greatest commandment in the Law?” 37 Jesus replied: “’Love the Lord your God with all your heart and with all your soul and with all your mind.’ 38 This is the first and greatest commandment. 39 And the second is like it: ‘Love your neighbor as yourself.’ 40 All the Law and the Prophets hang on these two commandments.”