And, actually, you just put your finger on it.
Just to push my little (imperfect) analogy a little further, it takes two things to turn iron ore into a functioning machine, it takes information and work, or to put it another way, it takes intelligently guided work. An engine is a repository of information, there is a huge accumulation of information and knowledge embedded in the design of that rather simple engine. Study the development (dare we say the evolution) of the design of diesel engines and you can see that the accumulation of knowledge comes slowly, at great cost in time and brainpower.
In software engineering the holy grail, so to speak, is software that can modify itself, that can adapt to changing circumstance without additional intervention from the programmer. If we manage this, it isn't evidence that programmers aren't necessary, it reflects rather an enormous accumulation of programming knowledge.
As for programs that replicate themselves, we already have those, unfortunately most of them are "malware" and we don't want them...
The machine analogy is pretty imperfect I realize, but when I look at a photograph of a living cell, I see what looks to me like a little micro-machine, complete with moving parts, with a little control system at the heart of it controlling the sequences, with information and commands being transmitted, ok not with wiring, but with some kind of electrochemical signals. Its pretty fascinating.
I try to imagine what it would take for me to design something like that, I almost think I could do it, I almost think I could design a cat for example, and mine would be less annoying than the original. Its just a matter of design and intelligently guided work in my (admittedly weird) little shop in the basement. I think I could do it. But the replication-thing would be a tough nut to crack, I admit. Oh, that and fitting the 286 in his head, I think I'd have to settle for a wireless router, and the processor would be in the attic. That will keep him close to home, at least.