One argument given for the existence of God is that it gives our life purpose.
Purpose - literally the results or ends of an action that was intentionally taken - is a concept that we intuitively "get". We know that a tiger attacks a gazelle to obtain nourishment, an elephant sprays water through its trunk onto its back to cool down or to wash. Other cause-and-effect relationships are less obvious. It sometimes appears that birds fly because its joyful, tiger cubs play because it feels good. We assign purpose to inanimate things as well - clouds are for rain, flowers are to feed bees; mountains are to climb.
It seems that trying to assign the purpose of our lives to something hypothetical is stretching what is already a pretty meaningful situation to an absurd length. I understand biologically that we are here to perpetuate the species. I live to bring my wife security, warmth, comfort and occasionally joy. I try to bring security and warmth and charity to others. I try to leave the world materially and emotionally better off than I found it.
These are meaningful things. They have profound meaning to me. A hypothetical being does not add or subtract from this feeling of deep meaning.