"But evolution doesn't make those developments improbable or coincidental." (not sure what you are on about with respect "Time's Second Arrow")

So, why are you not enslaved by your lizard overlords? 8) Homo is a bit of a johnny come lately and yet has managed to travel to the moon and back.

We only have a single extant example of hom sap to work with. We can work backwards, within reason, and still not manage to come up with a completely satisfying origin story. There is no way you can "derive" hom sap from first principles.