This still doesn't prove or explain in detail how those mutations and natural selection can build complex structures such as the genome.
Nothing in evolutionary theory needs to be proven. It's a falsifiable conceptual framework judged on its ability to unify observations, provide a mechanism for their existence, make predictions about what can and will not be found in the world, and to generate useful ideas that can be used to anticipate and at times manipulate nature successfully.
This theory does that, and that is why we continue to provisionally accept the truth of it.
And natural selection combined with variation in offspring explains how nature does it. If there are going to be variations in heritable DNA that lead to variation among offspring that then compete with one another for survival and scarce resources, biological evolution becomes inevitable.
Complexity doesn't drive this process, but the process predicts increasing complexity whenever it leads can occur incrementally and confer a selective advantage on the organism.
What could prevent it?.
Notice that there is no constructive argument for creationism, just criticisms of its alternative. No observation has ever made intelligent design more likely than Darwinian (naturalistic) evolution. Every observation ever made is consistent naturalistic evolution, which would be unexpected in an intelligently designed world.
Your implied argument is fallacious in two places:
[1] It is an implied argument from incredulity. Basically, your argument is that life seems too complex to you to have evolved without help. You just can't see how it could have happened, and so reject the possibility. Fine, but you understand that that is an opinion, and an unjustified choice. Many others have no problem seeing how nature might proceed as Darwin proposed it does. Personally, I can't imagine how a zipper works. I could not have imagined it much less invented it without such a concept. But that's not an argument that they can't exist, is it?
[2] You're also positing a more intractable problem as a solution to a lesser one. You think a cell is too complex to assembled itself and begun evolving, so you suggest something uncountable orders of magnitude more complex to account for it.
Neither of those is a sound argument, you have no other sound argument against evolution or for creationism, and you have nothing to replace a successful and productive theory.
