Yes, physically absolutely nothing. But conceptually they seem to to form this very generic function from inputs to outputs that neurons also form.
Agree and add, don't confuse the substrate for the computation. Of course it's also clear that we don't quite have a full and definite picture of what the computation consists of in the case of a biological brain as evidenced by our continued failure to accurately simulate even the simplest of organisms.
Only if you ignore almost every input and output that neurons have.
https://www.quantamagazine.org/ai-is-nothing-like-a-brain-an... https://pmc.ncbi.nlm.nih.gov/articles/PMC9665914/
This is why making more neuromorphic NNs is still an active area of research, although they typically all focus on another extremely simplified model (spiking neural networks).