Your line of reasoning is similar to "Food comes from animals and plants. But where does animals and plants' food comes from?". Do you want to go all the way up to the Big Bang?
You learn your ethics from a combination of your parents and society, and you update your beliefs during your life, you share them to a younger generation. Repeat since humans acquired a conscience until humans cease to exist. That's all there is to it.
You learn your ethics from a combination of your parents and society, and you update your beliefs during your life, you share them to a younger generation. Repeat since humans acquired a conscience until humans cease to exist. That's all there is to it.