Live began at least 3.5 billion years ago.

We don't know for sure if the life we have on Earth began here or was brought from another world by meteorites. Life on our planet has been literally the same since it began. We are the same first cell that we would consider to have been alive, which kept dividing for the past 3.5 billion years. We can be considered descendants from that cell, but in reality we are the same cell that kept dividing and changing gradually, working with its self, against its self, eating its self, etc. The sperm which fecundated the egg and the egg, which divided in your mother's womb for 9 months, are both descendants from that same original cell. What we call "birth" is something completely arbitrary which has meaning to us only because we reached that consensus. Without us to call it "birth", it would have no value. You didn't become alive today, nor 20 years ago, nor 20 years and 9 months ago.

tl;dr You became alive ~3.5 billion years ago, but you've only been aware of it for a few decades.