I'm important enough to be stably employed and to have people around me that care enough to keep me in their lives. I think that covers all the importance I actually need.
ItIsSoOver posted...
You don't need to be someone important to do something important.
This is also good advice. If you feel unimportant because you haven't done enough to improve the world around you, go do something to improve the world around you. There are always countless opportunities to do so, often pretty easily, you just have to look for them.
If you're eligible, donating blood is an easy one: Travel time included, it takes about two hours every 8-12 weeks and you might have a day or two of reduced physical stamina afterwards. It's virtually free, but every time you do it you can save multiple lives.