I think comparing us to Neanderthals didn't do it justice. Imo it's more like going from single cellular organelle-less life to a full blown human.

That said, today the "machine brains" we're building are closer to the single cell side of the scale than the human side.

I like this analogy better because cells never went away -- they just self organized into something greater than their whole, and I'd imagine the same will be (is?) True with 'thinking machines' as well