Evolution/regarding human brain
For my previous question, you wrote that it will not take millions of years for human brain to develop through evolution. We humans have not been able to produce a single living cell completely out of atoms till now. How could we imagine that we humans can produce a human being if we carefully design even in millions of years. If we humans cannot produce another human through careful design, does it not look like a remote possibility for nature to produce one.
Nature did not produce humans "from scratch." Pre-existing species were our ancestors, and those took billions of years to evolve from single-celled organisms. The human brain did not develop from a single-celled organism. It evolved from an ancestral primate brain in an animal that had characteristics of both humans and chimpanzees, and was the ancestor of both. That animal already had inherited millions upon millions of years of evolutionary change from a simple vertebrate ancestral brain in a fishlike animal.
Evolution does not create things de novo. It is more of a "tinkerer" that changes pre-existing things into slightly different things from generation to generation.
So the comparison of humans trying to devise a human starting with a single cell is not analogous to the evolutionary process. Unless you start with a single human cell and make yourself a clone. But we're not quite there yet, either.
Hope that helps.