Just because an observation is in the Bible doesn’t mean it originated there. The do unto others policy is the building block of any social contract that allows humans to cooperate for their survival. It doesn’t require a Supreme Being in order to be discovered or implemented.
Let me ask this then
Are valuations of things, like, say, chopping off little children’s arms, basically neutral? There’s no underlying sense of what is good and what is evil, that is shared across all humanity? Or if there is, where the heck did that come from?
What survival advantage led selflessness, or abhorrence of the torture of innocents, to an evolutionary advantage?
Apologies to C.S. Lewis, ‘Mere Chistianity”
Historical, the “golden rule” is no where else documented.
Most of the world then, and today, is screw the other guy before he screws you.
And, as documented in the Torah and Koran.