That's my point - computable functions are a [vanishingly] small subset of all functions.
For example (and close to our hearts!), the Halting Problem. There is a function from valid programs to halt/not-halt. This is clearly a function, as it has a well defined domain and co-domain, and produces the same output for the same input. However it is not computable!
For sure a finite alphabet can describe an infinity as you show - but not all infinity. For example almost all Real numbers cannot be defined/described with a finite string in a finite alphabet (they can of course be defined with countably infinite strings in a finite alphabet).
The point remains that we know of no function that is computable to humans that is not in the Turing computable / general recursive function / lambda calculus set, and absent any indication that any such function is even possible, much less an example, it is no more reasonable to believe humans exceed the Turing computable than that we're surrounded by invisible pink unicorns, and the evidence would need to be equally extraordinary for there to be any reason to entertain the idea.
For starters, to have any hope of having a productive discussion on this subject, you need to understand what "function" mean in the context of the Church-Turing thesis (a function on the natural numbers can be calculated by an effective method if and only if it is computable by a Turing machine -- note that not just "function" has a very specific meaning there, but also "effective method" does not mean what you're likely to read into it).
I was assuming the word 'compute' to have broader meaning than Turing computable - otherwise that statement is a tautology of course.
I pointed out that Turing computable functions are a (vanishingly) small subset of all possible functions - of which some may be 'computable' outside of Turing machines even if they are not Turing computable.
An example might be the three-body problem, which has no general closed-form solution, meaning there is no equation that always solves it. However our solar system seems to be computing the positions of the planets just fine.
Could it be that human sapience exists largely or wholly in that space beyond Turing computability? (by Church-Turing thesis the same as computable by effective method, as you point out). In which case your AGI project as currently conceived is doomed.
If you can do so, you'd have proven Turing, Kleen, Church, Goedel wrong, and disproven the Church-Turing thesis.
No such example is known to exist, and no such function is thought to be possible.
> Turing machines (and equivalents) are predicated on a finite alphabet / state space, which seems woefully inadequate to fully describe our clearly infinitary reality.
1/3 symbolically represents an infinite process. The notion that a finite alphabet can't describe inifity is trivially flawed.