"The meaning of life is to give life meaning" "Helping people" might be a good meaning for life. "I am here to help people." You could do worse. — Bitter Crank
So why, presumably, would "killing people" not be a good meaning to give to life? The problem for me with the idea that meaning is only something we assign to life is that I think meaning and ethics are aspects of one metaphysical reality (for lack of a better term), and so they can't be separated. For us to assign life a meaning, the meaning has to pass some sort of general consensus of being a decent choice. There's still an ethical litmus test at play. That's not at all to say that we
don't assign our own meanings to our lives. We certainly do. I would even go so far as to agree that at least almost any meaning we ascribe to our lives is just "a theoretical overlay" as you say, but the problem here for me is that we create an unnecessary dichotomy between subjective and objective. It's true that we subjectively project meaning unto our lives, but this in no way excludes the possibility of a transcendent meaning also existing. The reason I think we do this is because, historically, for most religions, a transcendent meaning was assumed, and now the idea that we project meaning has historically grown out of the old understanding. A teenager may wake up one day and realize she doesn't
have to follow her parents rules. She very well has the capacity to do as she likes, she can, in a sense, make her own set of rules for herself. The parents may punish her for this, she may disobey in secret, or the parents might just not care, but regardless, she now has this power. And she may, years later, realize that at least some of her parents rules would have been beneficial to follow. In my view, the whole process is necessary: the initial rules that govern the raising of a child, the rebellion from the rules, and the closure of looking back and seeing value in some, not all of the rules she rebelled against. And with a mature view, she can also realize the benefit of her rebellion as well.