Do you know where we came from? True fact : We came from stars
When old stars die, they explode in this gigantic explosion, which makes a nebula. Nebulas are clouds of gas and dust. That's where baby stars grow. All the gas and dust gets compressed, gravity sucks them in and they turn into stars. The bits that don't turn into stars float around in space as planets or moons or comets, and if the conditions are right, plants and stuff start to grow and people are born. So we're all made of bits of old stars. But it's a cycle. Because after millions of years the new star gets old and tired too and it explodes and more baby stars get born. If the old stars didn't die, you'd never get new ones.
Here's another true fact. Carbon, hydrogen, oxygen and nitrogen are the elements you need for life. And if you look at comets, you see that they have pretty much the same proportion of these elements as we do.