And no doubt you perceive that all this "unbelievable complexity" was somehow generated from random unguided forces. Forces which are demonstrably destructive as opposed to creative.
As other have pointed out unguided but not random - indeed the very opposite of random as they are driven by fundamental energetics.
So of course you can develop complexity and 'order' in this manner. Here is a simple example - mix 2 simple molecules - water and an amphiphilic lipid. In your understanding that order and complexity cannot happen without some kind of supernatural guidance, you'd predict a random mix of the molecules. But that's not what happens - they naturally self-order into the most ordered structures, including perfect water filled lipid spheres each of which has a coating exactly two molecules thick - no more and no less. Astonishing complexity that occurs naturally. Why does it occur - because it is the lowest energy state.
The notion that complexity can only arise via the guiding hand of something more complex is a route to nowhere as that complex guiding hand must have been generated by a more complex guiding hand and or on ad infenitum. Nope - the only credible argument is that complexity (as we see it) arises from lower levels of complexity - bottom up, self assembled so to speak. And this is exactly what we see in the complexity of our world, driven by fundamental energetic principles.
And no doubt you perceive that every one of the billions of accidental mutations involved gave sufficient benefit in their own right to be selected by giving survival advantage.
Yup, that's right - and I can show the process in the lab to you any day you want. It is standard practice when genetically modifying a micro-organism for research purposes to also include an antibiotic resistance. To select just those with the mutation you want you challenge the cells with the antibiotic in question and only the modified microorganisms survive. Evolutionary principles demonstrated in a dish in a couple of days.
Is there no limit to the specific complexity this crude process of evolution can generate?
It is theoretically limited by the number of genes we possess and therefore the combinations of genes turned on and off and their individual structure (where mutations come in) - humans have about 20,000 genes. Add to that the fact that some genes code for proteins that modify other proteins and you add to that complexity. Throw in the notion that we are dealing with interacting networks of proteins etc and you have an astonishingly complex set of possibilities generated by evolution.
Now some other species have more genes again, and therefore greater propensity for complexity. To understand this we need to recognise that while we may consider 'complexity' in terms of brain function and higher consciousness, this is a fairly human-centric approach. In some respects we are relatively simply organisms with a pretty linear lifecycle and we perhaps don't need so many genes. Compare humans with some species whose life cycles go through distinct phases, distinct sets of genes that generate the larval and adult stages, and further ones that are required for the metamorphosis between those stages. Sure those organisms don't have the neural complexity we have (but that doesn't necessarily require huge numbers of genes, but adaptive neural networks), but in other respects their lifecycles are way more complex than humans.
