I'd say yes and no. It does matter to you and that should be enough. And if it means something to other people...even better. If you put your focus a bit further from earth...say 2-3 lightyears and and look at earth and what one person does from that angle...no you don't matter
but if what if you could see ALL the changes in the world taking place over a thousand years. Follow each single person, and watch as something miniscule reverbirates (is this the word i meant to use??) escalate and spread exponentially through time.
Imagine leonardo da vinci had decided he wanted to be a professional swim teacher? Or einstien a race car driver? What would the world be like if King Henry the I was overthrown by peasants and the worlds first democracy was born Hundreds of years earlier? Even more recent things like the assasination of JFK or Martin Luther King being avoided.
All these would of changed the world IMMENSELY. And are they all not but a single human in the world?
I believe every choice you make has the chance of becomming something incredible, or possibly horrible, it just depends on the circumstances.
Have you ever stepped out into a street, only to have a car RUSH past, missing you by merely inches. Now did you ever think back to how you forgot to lock your door when you left home, and had to backtrack a second to do it? What if you hadnt decided to lock the door, and went on with your day, a few short seconds ahead of where you were, would you have bene hit by the car? Maybe. Maybe not. Maybe the driver of the car would of seen you, swerved, hit an oncomming car, which began rolling maniacly towards a photo shoot outside a small boutique. You notice and quickly run over, throwing the model out of the way. You both fall in love and she marries you.. Not so likely, but you see where im going.
Take that into concideration. how many INFINITELY unimportant decisions have you made, that one way or another may have changed the path of your life forever, without you ever having the slightest idea.
So to answer your question: Yes, i do believe everyones life matters. From a handicapped senior citizen to paris hilton to you, every person on this planet could somehow indirectly influence your life, for better, or for worse.