Each and every one of many billion transistors in a GPU works due to certain quantum effects on P-N junction. That does not mean GPU computation is nondeterministic, unknowable or magic.
Sure, but it's designed to minimize the chance that a quantum fluctuation could change the outcome of a computation, right? Whereas in the brain that might not be the case. A lot of the "interesting" neural activity (e.g. relating to decision making, language, etc) happen in highly sensitive dynamical regimes: on a threshold of firing, or activating one neural population vs another. (Arguably you can get the same effect in an artificial network by adding true random noise though!)
It's not implausible that evolutionary pressures made the brain robust enough to withstand parasitic signals. We know that most people think in similar, predictable ways.
I used a qualifier because (as you certainly know) people will not pass a chance to nitpick. I have no energy to argue about neurodivergent or Ramanujan, even though I still believe the basic physics of their thinking is identical. Hence "most".
My argument was straightforward to follow but if there's something unclear let me know and I'll chew it down.