Who was the first to interpret scripture subjectively in a way that hadn't been done before, but then the early church accepted it?
My answer, in a word:
The Pharisees in the first century had Moses, the Psalms and the Prophets: the Hebrew Scriptures. (And Jesus didn't dispute what these Scriptures were--their "canon" if you will). They used these Scriptures to condemn Jesus as a blasphemer. It was their interpretation of these Scriptures that informed their expectations of a political deliverer and a physical fulfillment of Messianic prophecies. Jesus came declaring himself to be that Messiah, preaching a Kingdom that is “within you” and “not of this world.” He appealed to the Scriptures--their Scriptures—when he said, “this day the Scripture is fulfilled in your hearing.”
In Luke 7, John the Baptist sent his disciples to Jesus to inquire of him, “Are you the one who was to come, or should we look for another?” Jesus answered by quoting from Isaiah. He was in effect saying, “Yes, I am the one.” And the evidence he gave to John for this—the confidence he wanted John to have—came from the Scriptures that John trusted. The Scriptures that the “traditionalists” of that day disbelieved! (Or misinterpreted?)
In John 5, Jesus said to the Pharisees: “You search the Scriptures because in them you think you have life, but they testify of Me.”
So Jesus broke with the traditional interpretations of His day—and from those who were in authority—and the early church went with His dissenting view. At least for awhile.