It was our ancestor Jacob who gave us this well; he and his children and his flocks all drank from it. You don't claim to be greater than Jacob, do you?”
This means that he had to become like his people in every way, in order to be their faithful and merciful High Priest in his service to God, so that the people's sins would be forgiven.
Our High Priest is not one who cannot feel sympathy for our weaknesses. On the contrary, we have a High Priest who was tempted in every way that we are, but did not sin.