Tell me why evolution would require all of those combinations to be tried?

Edit: Microsoft Windows 10 is 9GB. It would be impossible to try 8^9000000000 different programs. Yet, Windows exists, and most of us believe it's contained in those 9GB.

Exactly the opposite. Just because there are so many possibilities doesn't mean that all of them have to be tried or make sense.

You wouldn't code that way and nature doesn't either.

If you just want to talk about how computationally tractable it is, the math is trivial. Optimize one base pair at a time. Now it's an O(4) problem repeated over a billion generations, most of which are bacteria where a generation is measured in minutes.

In practice the changes happening in each generation are all sorts of different rearrangements, but that's different from proving the basic and obvious fact that when you have multiple steps you don't have to spontaneously create the entire solution at once.

Bogosort will never ever sort a deck of cards. Yet it takes mere minutes to sort a deck of cards with only the most basic of greater/less comparisons. Even if your comparisons are randomized, and only give you the right answer 60% of the time, you can still end up with a sorted-enough deck quite rapidly.

(Why sorted-enough? Remember that reaching 'human' doesn't require any exact setup of genes, every single person has a different genome. It just has to get into a certain range.)