Consider the priests are ordained by the bishops who are the successors of the Apostles, they too were given the authority to forgive sins.
Jesus granted the Apostles the authority to forgive sins clearly in John 20:19
"On the evening of that day, the first day of the week, the doors being shut where the disciples were, for the fear of the Jews, Jesus came and stood among them and said to them. “Peace be with you.” When he said this, he showed them his hands and his side. Then the disciple were glad when they saw the Lord. Jesus said to them again, “Peace be with you. As the Father has sent me, even so* I send you*.” And when he had said this, he breathed on them, and said to them, “Received the** Holy Spirit**. If you** forgive the sins of any, they are forgiven**; if you retain the sins of any, they are retain.”