Billions of years ago there were no elements, just protons and electrons - they grouped together to form hydrogen (one of each particle). Then through weak gravitational interactions they began to form into clouds, massive clouds. Which eventually become denser and denser and their gravity becomes stronger and stronger until they crunch down to form a star, which is essentially a massive ball of hydrogen whose gravitational force causes the hydrogen within to fuse together releasing massive amounts of nuclear energy (like an atom bomb) and converting the hydrogen into partly heat and light radiation and partly other elements. Hydrogen + hydrogen = helium, hydrogen + helium = something else and so on and so forth until eventually you get everything from gold to plutonium.
This is how the matter which makes up our body (which is still about 70% hydrogen since the universe is 90% unconverted hydrogen) formed, so yes, we did come from stardust.
