Even if you discount the role of the whole body as an integrated system, signaling and talking to itself, coordinated by the brain... you're still talking about

Even if you discount the role of the whole body as an integrated system, signaling and talking to itself, coordinated by the brain... you're still talking about 16 billion neurons in the cortex alone. That may sound like a number we can approach or exceed with modern tech, but neurons are not transistors. Those 16 billion neurons in the cortex form over 140 TRILLION connections through synapes. Those are both computing elements as well as memory. There's no comparison, not even close. As a bonus we don't each require a giant warehouse to house us, we don't require a vast supply of water, nor do we require a personal dedicated power plant.