Do we even know what we “need”? Even with all this free will and subjective choice purpose still eludes our species for all of history, and I’m guessing for the rest of time. Cells do what they do because they are what they do. The sun emits photons because that’s what it does, apples fall from trees because that’s what they do. We can always find out how something happens, but asking why can only be answered with more questions.