We know so little about how the brain works it's hopelessly hard that we would be able to emulate it. We should maybe instead focus on making AI think the same way airplanes fly. Meaning studying the brain, especially the human brain is so hard it's no wonder we aren't anywhere near understanding intelligence, free will, and other aspects. Science is just such a hard thing to do! It's also possible we simply aren't capable of understanding those things because we have limits to our intelligence.

EDIT: Great talk from Chomsky https://youtu.be/TAP0xk-c4mk