I don't think this desire to know the purpose of life comes from anything truly natural, though. It's from religious conditioning which has been going on for centuries. It comes from an idea being pounded into children literally since birth. Among other things, it involves being inculcated with the idea that there is a purpose to life, usually propagated by those who don't know what it is either.
Some may look for God's help, but only because they've been trained and conditioned to do so all their lives, including the part of their life when they are most impressionable, such as during their formative years.
I (and I'm sure many others here) can attest to this myself. We've all heard about God and that He created all the things around us. Many of us have heard about the notion that there is some purpose to all of this.
But I would submit that, even assuming the existence of a "God" who may have created all the things that we see, even that does not imply any special "purpose," in and of itself. Our existence could have been an unintended accident or a failed experiment.
When you really look it, religious belief seems to be more about "us," as humans, rather than about "God," which is mainly a nebulous, vague, indefinable, indescribable concept overall. But religious stories tend to focus on human activities and how a supernatural being takes a special interest in our lives and what we do.