> our belief that only biological entities can think

Whose belief is that?

As a computer scientist my perspective of all of this is as different methods of computing and we have a pretty solid foundations on computability (though, it does seem a bit frightening how many present-day devs have no background in the foundation of the Theory of Computation). There's a pretty common naive belief that somehow "thinking" is something more or distinct from computing, but in actuality there are very few coherent arguments to that case.

If, for you, thinking is distinct from computing then you need to be more specific about what thinking means. It's quite possible that "only biological entities can think" because you are quietly making a tautological statement by simply defining "thinking" as "the biological process of computation".

> thinking is a core part of our identity, unlike swimming.

What does this mean? I'm pretty sure for most fish swimming is pretty core to its existence. You seem to be assuming a lot of metaphysically properties of what you consider "thinking" such that it seems nearly impossible to determine whether or not anything "thinks" at all.