My perspective as agnostic
What are the important things in life?
I do not know what the important things in life are at this very moment but can I do something about it? Can I expose myself to doing more important things and doing less of the nonimportant things as I have no idea which particular activity will stick and will turn out to be meaningful?
So If we are totally ignorant about the outcomes of our actions we should probably diversify our effort in doing different things and see which one survives. But aren’t we getting into the problem of diluting our efforts too much and not finishing a single thing, becoming a generalist without any specialty who has nothing special to offer?
The “barbel” strategy described by Nassim Taleb may come in handy to tackle the above problem. So you start experimenting in different areas in life and in some experiments you get positive feedback, you feel a passion and you strive for mastery. Obviously, you should focus on these things with a significant portion of your time and resources but to be somewhat diversified you should allocate some smaller part of your time and efforts to “random” activities outside of your comfort zone.
Eventually, time and survivorship are the only true indicators of importance that the Universe cares about. So which things can outlive our mortal bodies :
Genes – having offspring and copying your genes
Memes – generating, copying, and transferring viral ideas that are sustainable
Craft – creating something that is robust that has a long life
Being happy, enjoying oneself, and having fun may be a byproduct of your journey but they are not necessary and you could probably do important things with less fun.