You know i struggled with this question myself. For many its a subjective truth. The answer for me came when i was engaged to a woman and helping to raise her child for some time. I had purpose. A reason. That was my meaning of life. To give to others. To help a new soul grow into this world as best as i could and to be as supportive a husband as i could to my partner. Giving more love than receiving.

To me thats the meaning of my life. From a biological standpoint it makes a lot of srnse too