I think that life is a journey - each of our lives may have positive effect on the lives of other human beings as well as on our environment in overall if we will take that under consideration (so there is this aspect of maintaining civilisation that other ppl before us maintained and built for us, therefore also some responsibility for future generation having it better - because why not to help them? Many before us created things and ideas we can use for our wellbeing ). Most of us will have only very small impact for "doing things right" for the others but it still matters.
I also think that parenthood makes you understand better that your own importance is not really that relevant. The solipsism in each of us (this feeling that world is what you experience through your eyes only and it's all that really matters and that you need to have an impact on this world) eventually slowly dies out - it's ok, there will be others that will try to change the life for the better.
There is also a pleasure of understanding the world better that may bring you closer to your own purpose - reading about it, understanding it better, travelling to the places that you know you need to visit, understanding things you feel you need to understand (but you don't know yet why).
There is also one common thing in all humans - with passing years most of us get more connected with the nature, ppl that hated spending time in the outdoors suddenly start taking care of the gardens, taking more walks or just having some flowers in their apartments even if they didn't care about them for most of their lives. I think most of us will hear this call of Mother Nature this way or the other.
I find it somewhat strange but I'm pretty sure that I will not be afraid of death on the rational level when it will come (even if biological reaction may provide mixed emotions about this fact). I am and was supposed to die eventually since I was born mortal, so being afraid of it makes little sense. I think we should all be very happy that we got chance to experience this world as humans, not as any of the lesser species.
I am pretty sure that we are an effect (not necessarily intended) of creation of vastly superior being (whether we will call it Great Architect or God - it doesn't really matter) but like ants do not understand their purpose in ecosystem, we do not understand really ours purpose - however it is certain that some logical purpose is there and invisible web of connections that we understand only partially and discover slowly through scientific discoveries in physics, math, biology or chemistry is there for us, like a resource that may be used for our greater purpose. We do not need to be individually responsible for this journey of understanding the purpose of life and universe - it is sufficient to do the maintenance tasks and allow other, more bright intellects, to do this work, discovery after discovery, for us.
Therefore, there is plenty of purpose in each of our lives. It is just a matter of noticing it and identifying which is the most important for you (answer to this question may be complex but it is perfectly fine if that's the case).
