I think reason generates a meaning crisis, by finding fault with any assigning of a purpose that doesn't reduce to something trivial or arbitrary. Survival is the function of animals, but not people. The pursuit of pleasure (hedonism) is part of what we think of as the good life, but so is duty or self-sacrifice. Is there a special purpose worth sacrificing ourselves for, something we ought to be striving to achieve? Or is it different for each individual, depending on personal taste?

If we know what we are, that may dictate our normal behaviour but not necessarily our "meaning" or purpose, assuming we don't want to commit the naturalistic fallacy. Our limited freedom means we needn't conform to what's normal since we can choose to be abnormal. Indeed, personhood is anomalous in the animal kingdom, and countercultures defy conventional wisdom.