But in theory, would it be possible to genetically engineer a simple life form, like a bacteria, to eventually produce a human, in a process similar to the kind of metamorphosis you see in insects. Of course, this the bootstrapping code would take quite some space, but if we could do that (at least in theory), it essentially means that all you need to make practically any living being is a single generic cell and a few megabytes worth of data encoded as DNA.

I mean, when we get infected by a virus, our cells are able to produce a completely different life form (if you consider viruses life forms), so why not going from a bacteria (which can also be infected by viruses) to a mammal. It will obviously take a lot more code, and evolution can't get us there, but the idea is similar.