Wow, those are some big questions you are asking.
Well, here's my take:
I believe that humanity has a job to play in the story of the Universe. I think we are destined to move beyond this world and fulfil a role. I don't think the individual really matters, generally speaking, but it is about our collective impact.
Obviously, some remarkable individuals do have an impact, but most of us are just foot soldiers, destined to live ordinary lives and die. And honestly, I don't think there is much to be gained from pondering that. The life of the individual is futile, and within 50 or so years of our death, it will be like we never existed.
Which is a thoroughly miserable thought! So don't think it!
Remember the golden rule: treat others as you would want to be treated, and try and have some fun along the way.
Having children changed a lot for me. I can try and make them better than I am, and hope that they go on to be a remarkable individual. And I hope that they don't spend too much time thinking about the futility of exsistence!