Again, you're going wildly off the rails in your logic. Sure, "executable by a human" is part of the definition for Turing machines, but that's only talking about Turing-specific capabilities. If you want to argue that a Turing machine can emulate the specific definition of Turing machine capabilities that humans can perform, that's fine. But you're saying that because humans can ACT LIKE Turing machines, they must BE Turing machines, and are therefore emulatable.

This is the equivalent of saying "I have set up a complex mechanical computer powered by water that is Turing complete. Since any Turing complete system can emulate another one, it means that any other Turing complete system can also make things wet and irrigate farms.

Human intelligence is not understood. It can be made to do Turing complete things, but you can't invert that and say that because you've read the paper on Turing completeness, you now understand human intelligence.