I wonder if there isn't some fundamental misunderstanding here. What if it's not "just the neurons". If you found a Regency TR-1 radio you could wonder "how can this 4-transistor device produce a continuous stream of music, much like Spotify, which requires billions of transistor to run?". Of course, the radio also has an antenna, which is a completely different device than a transistor.

The device running Spotify may also have an antenna, but I hope you get the analogy. My analogy is not meant to be taken faithfully, so that we need to start looking for antennas now instead of neurons. I am just saying that maybe the neuron-counting game is not the only thing. Maybe there is something else -- not magical, not divine, but physical and as-of-yet unknown. Humanity didn't always know everything, and maybe still doesn't.