Creationists believe that humans were created by god for some purpose, or at least were created by a purposeful god. This purpose defines the meaning of their lives, so without it life would lack meaning.
An evolutionary biologist could support that proposition – that the way we were “created” provides meaning. Life, including humans, develops by evolution, a non-random adaptive process. We can’t ascribe purpose to it, as it is not (likely) a conscious process. This does not however, lead to the conclusion that life lacks meaning. The evolutionary process is elegant and some of it defies logic (i.e. emergent behavior), as such it is full of meaning. It’s not just how we were created but what we are that matters. Human beings, as entities with free will, have an unlimited ability to create and define the meaning of their lives.
Australian aborigines have “dreamtime” – a creation of the world with a past, present & future that is porous to the dreamtime. Every moment is totemic & represents a meaningful symbol beyond time. Right now I’m the quintessential totemic person at her computer writing about time and meaning.