El Cid said:
Throughout all of human experience, purposes have only come from a personal intelligence.
That's just not true. We humans have some basic survival instincts that give our lives purpose, but they don't come from a personal intelligence, they are a part of our basic nature. We don't sit down and think about eating for the purpose of survival in order to get the instinct to eat, the instinct is there from birth.
We share this instinct to eat which gives our lives a purpose with animals who don't have human intelligence but have said purpose to eat.