There is a core to the Law, the Torah. It is the ethical demands summed up in the 10 Commandments, but presented throughout. Jesus did not change these; in fact his goal was to emphasize them when other would've made them secondary to tiny prescription of ritual purity. Around that core is the rest of the 613 commands of the Jewish Bible. Jesus kept those in his day, but the Apostles—interpreting what he said here and elsewhere—felt safe in making those ritual requirements optional, while still insisting on the moral core found in the Decalogue and highlighted in Jesus' teachings. Finally, around that second layer of the Mosaic Law, there had grown up traditions that were good up to a point, but that Jesus sees the people choosing to focus on while "neglecting the weightier things of the Law" through their focus on picayune things of manners and customs while turning a blind eye to what really mattered: the ethical choices of the heart. In the heart, in the will, lies virtue and vice, goodness and evil, purity and that which defiles.
(Apologies, I thing I twice say "Mark 6" instead of Mark 7. I must've still had John 6 on the brain.)