Where does morality come from in Buddhism?

I have a hypothetical question. Let's say I don't believe in karma, reincarnation, or any deities of any sort. I also saw in some texts and videos that, to achieve higher awareness, I should not define good or bad either. That I should be equanimous towards everything. If there is no distinction between good and evil, where does morality come from then, in the absence of karma? How do I justify my inclination toward doing good to humanity? Is my question nonsensical? Please help me resolve this conflict.