This is a time horizon thing though. Over the course of future human history AI development might look exponential but that doesn’t mean there won’t be significant plateaus. We don’t even fully understand how the human brain works so whilst the fact it does exist strongly suggests it’s replicable (and humans do it naturally) that doesn’t make it practical in any time horizon that matters to us now. Nor does there seem to be fast movement in that direction since everyone is largely working on the same underlying architecture that isn’t similar to the brain.