> they're CPU cores,
No, they are really not.
A Neuron on its own is capable of exactly one thing, and that's signal integration from it's dendrites. That's it. Wait until the excitation potential reaches the point where the Potassium channels switch and boum: Signal cascade goes down the axon.
The only moderation a single neuron is capable of, is varying signal resistance to filter out repeating noise.
> https://www.quantamagazine.org/how-computationally-complex-i...
Computational complexity doesn't indicate computational capability.
There are any number of systems that stubbornly refuse to be capable supercomputers, despite being incredibly hard to simulate.
Accurately simulating every aspect of the liquid flow through an acorn leaf, with it's billions of micro and nanometer channels, would easily be one of the most difficult tasks in the history of computing, and yet, acorn leaves are not even capable of the simplest thought, and the entire modus operandi of water flow through an entire tree can be accurately summarized in a simple 1-page diagram.
Every single muscle fiber with its trillions of moving cytoskeleton components, has a much higher complexity than a neuron, that doesn't mean muscles are supercomputers.