But even if so, Jesus plagiarized it from Rabbi Hillel:
These two great scholars born a generation or two before the beginning of the Common Era are usually discussed together and contrasted with each other, because they were contemporaries and the leaders of two opposing schools of thought (known as "houses"). The Talmud records over 300 differences of opinion between Beit Hillel (the House of Hillel) and Beit Shammai (the House of Shammai). In almost every one of these disputes, Hillel's view prevailed.Rabbi Hillel was born to a wealthy family in Babylonia, but came to Jerusalem without the financial support of his family and supported himself as a woodcutter. It is said that he lived in such great poverty that he was sometimes unable to pay the admission fee to study Torah, and because of him that fee was abolished. He was known for his kindness, his gentleness, and his concern for humanity. One of his most famous sayings, recorded in Pirkei Avot (Ethics of the Fathers, a tractate of the Mishnah), is "If I am not for myself, then who will be for me? And if I am only for myself, then what am I? And if not now, when?" The Hillel organization, a network of Jewish college student organizations, is named for him.
Rabbi Shammai was an engineer, known for the strictness of his views. The Talmud tells that a gentile came to Shammai saying that he would convert to Judaism if Shammai could teach him the whole Torah in the time that he could stand on one foot. Shammai drove him away with a builder's measuring stick! Hillel, on the other hand, converted the gentile by telling him, "That which is hateful to you, do not do to your neighbor. That is the whole Torah; the rest is commentary. Go and study it."
"Do unto others as you'd have them do unto you" is revolutionary.
The Rule -- especially if we agree as to it's mathematical backing -- precedes the Lord's walk on earth. There were smart and wise people who understood this B.C. But it did not become the cultural foundation until Christ.
The Old Testament's rule was eye for an eye.