I understand you have to think this way, but this is a very selective reading. There is an exchange between engineering and biology, but a large amount of the complexity in biology is best explained by incremental addition of parts, more like a goldberg machine than a fresh de novo design. This is an immensely difficult way to design things for human designers, which is why we have such difficulty engineering biological systems. This complexity, however, actually improves the odds of biological evolution. What biology shows us is that life is not designed at all how a human designer would design it, and it cannot be understood with out engaging its deep history.
I know you are not talking about common descent here, but it is worth asking. Do you affirm common descent? If not, why did not God make it more clear that common descent is false?