Here are just a few examples. In truth the Golden Rule is so incredible common throughout history that those who study ethics generally hold it to be a fundamental principle found in human culture on every continent. Don't get me wrong, it isn't a bad general rule. But it is as much 'typically Christian' as the 'don't kill others' commandment: you find it in the overwhelming majority of religions throughout the ages. You have a couple of basic rules that are seemingly essential for a tribe to prosper, and these have been handed down from generation to generation, religion to religion, civilization to civilization, in one form or another. Different continents, prophets, gods, beliefs, origin stories etc etc, but in the end more or less the same stories. Be nice, be thankful for what you have, try not to pillage and assault others too often, work hard, don't lie.Have you got a reference for the golden rule predating Jesus? I'm genuinely interested.
tl;dr if you can think of an alternative way to phrase the Golden Rule, someone wrote it down thousands of years ago.The Pahlavi Texts of Zoroastrianism (c. 300 BC–1000 AD): "Whatever is disagreeable to yourself do not do unto others." Shayast-na-Shayast 13:29 and "That nature alone is good which refrains from doing to another whatsoever is not good for itself." Dadisten-I-dinik, 94,5
"Avoid doing what you would blame others for doing." – Thales (c. 624 BC – c. 546 BC)
"Do not do to others that which angers you when they do it to you." – Isocrates (436–338 BC)
Siddhartha Gautama, c. 623–543 BC "Hurt not others in ways that you yourself would find hurtful." (Dhammapada 10. Violence)
Confucius (551–479 BC):"Never impose on others what you would not choose for yourself"
— Mozi, c. 400 BC. "If people regarded other people’s states in the same way that they regard their own, who then would incite their own state to attack that of another? For one would do for others as one would do for oneself. If people regarded other people’s cities in the same way that they regard their own, who then would incite their own city to attack that of another? For one would do for others as one would do for oneself. If people regarded other people’s families in the same way that they regard their own, who then would incite their own family to attack that of another? For one would do for others as one would do for oneself. And so if states and cities do not attack one another and families do not wreak havoc upon and steal from one another, would this be a harm to the world or a benefit? Of course one must say it is a benefit to the world."
"A man should wander about treating all creatures as he himself would be treated." — Sutrakritanga, 1.11.33 (+-400 BC)
"If the entire Dharma can be said in a few words, then it is—that which is unfavorable to us, do not do that to others." — Padmapuraana, shrushti 19/357–358 (hard to date, 400-1200BC)