> If you look at primitive reflexive responses in insects, you see that the underlying neural pathways are, at the micro level, different for each individual. In other words, the brain develops according to environmental feedback

Let's take a look at this video [0] of a newborn foal learning to walk. It does so in approximately 30 minutes, without any explicit reinforcement from anyone (its mother is supportive, but doesn't explicitly encourage or discourage any particular behavior - it is simply caring for the animal). It also shows the ability to interpret visual input from its eyes, to recognize objects such as its mother, and the ability to produce and execute simple plans (get up, go to eat). If you look at a million million such foals, you will never see one behaving differently in any significant way - for example, not a single one will start grazing, or try to eat it's mothers teats instead of suckling on them, or try to suckle at thin air and so on.

The only possible explanation for this type of rapid discovery is that it was born with these abilities "built-in", trained by evolution over countless millions of years. There is no adaptation going on: the animal is just born with the "computing infrastructure" to perform these tasks. Of course, there is further learning to be performed later, and the algorithms for that are also part of the genetic endowment.

Note that "computing" is an extremely general notion, and artificial neural networks at least are absolutely computers. Whether biological neural networks are also computers is not settled science, to be fair, though it is hard to even imagine today what else they could be.

> Think of memory. Memories are not stored, if they were, the brain would have to remember where they were stored, ad infinitum.

By this argument, computers would be unable to store information as well. That's not to say that I imagine animal memory is equivalent to RAM or HDDs - they are vastly different. But RAM is definitive proof that it is possible to store and retrieve information without reaching an infinite regress of "who remembers where the information is stored".

> Without stimuli, including interior/private thoughts, memories don't really exist.

If internal states of the brain can be considered stimuli, than the entire concept of operant conditioning becomes a trivially obvious idea, a metaphor for almost anything. By this notion, CPUs can also be said to work based on operant conditioning: electrical pulses are "internal stimuli" that shape the behavior of the integrated circuits. Atoms themselves "learn" to decay when receiving stimuli from a neutron particle hitting the nucleus.

> An animal or person can't execute complete motor performances according to some computational scheme

Again, we have definitive counter-evidence to your statement from the world of computing. Modern robots that are able to walk decently in rough terrains are in fact doing so based on sophisticated (statistical) computational schemes. If you want to claim that ANNs are not computation per se (which is wrong), we can fall back to industrial robot "arms" which have existed for decades and are able to perform sophisticated environment-based movements while being manually pre-programmed using mathematical control theory (systems of differential equations).

[0] https://www.youtube.com/watch?v=7-kQJzd7muA