Deep down the brain is 100% discrete: Neurons are either firing or not. To me, the brain's biggest mistery is how it goes from this to doing all the analogue stuff, and ends up with our capacity to deal with symbols.
Buuuttt... it's possible that few if any of those things are needed to capture the essence of a brains' functionality.
Maybe it's simply a matter of size. Maybe some configuration tweaks. Perhaps a different architecture.
We simply don't know - yet.
I'm pretty sure all those things being dismissed are the essence of a brain.