A leaf in a spray on a twig on a branch at the outer edge of the crown of a thirty-foot tall forest tree surrounded by hundreds of others could probably (if it could reason) trace a path directly back to the roots, and as a consequence believe that all the previous growth had happened with the purposeful design of producing itself.
However, starting from the root end of the system, its tracing could have followed hundreds (thousands? millions?) of paths which would have ended in different leaves. If it had budded on a different twig and been eaten by a passing caterpillar, it wouldn't have existed and been able to look back at its "inevitable" existence.
If the result of one of the thousands of mutations that produced our "inevitable" uniqueness (or the uniqueness of any living thing) had been that it was eaten at once by a predator, or wiped out by a drought, we would not be here to look back and say that there was a design to our, or anything else's, evolution.
In retrospect the route is obvious by the footprints left, but from the start it is a trackless waste to be wandered through in trial and error, and the errors could have resulted in our never existing, and never knowing that we didn't exist. For egocentric beings with the ability to reason and plan ahead, that is a hard thing to accept.