With a crust forged by cooled magma oceans, this planet formed land, sea, and sky on its surface over 500 million years by vaporizing the water inside comets to create 200C rain, and absorbing C02 from the atmosphere into its oceans. And then, four billion years ago in the deepest regions of the ocean, a miracle happened.
From the ingredients delivered by a Heavy Bombardment, you started out as a soup of inorganic molecules heated by hydrothermal vents. But through constant self-replication, autocatalysis, and the emergence of a lipid membrane, you broke out from the chemical world as the Last Universal Common Ancestor (LUCA), the first living being. In your dormancy, you hear a soft voice...
"Life... can you hear me?"
You had no intent to respond, just absorbing the heat.
"Life. Come on, awaken to my voice. Wake up."
All you could do was snore.
That got you to wake up and listen. You mumbled irritation upon this awakening because even for a goddess, that is a rude thing to do. She apologetically cleared her throat and uttered, "My bad." Then she spoke in her normal, ethereal voice. "Life, my darling child, this is the beginning of your journey. The body you bear is the template on which countless beautiful things will be grown. You can't leave the primordial soup as of yet, but there is enough here that can prepare you for the rest of your evolutionary odyssey. Once you've left from within me, you're on your own. Ahead of your time will be many ordeals, and you will face many difficulties. But you musn't get discouraged. Live, live, and live some more. Because to survive, is to evolve. I will record everything about us inside of your bodies. I hope that you grow and develop in peace. Only once you've fully matured can we see each other again as equals. I believe in your success. Except... never mind. Just be careful. Let us work hard together, because without me, you all would not be able to survive, and without you, I have no meaning. Please allow me to be the first to say welcome home 4 billion years from now. Now, be off on your journey."
You couldn't hear her after that. It was just you and a motherlode of free floating nutrients that is being naturally replenished. Alongside the glucose and amino acids and fatty acids, there are also high amounts of dissolved iron, hydrogen sulfide, and manganese in the ocean that have been released by the hydrothermal vents. Right about now, you feeling a bit hungrier, with purpose.
You gently drift within this soup, absorbing other building blocks as life as you go. One particular molecule, RNA, was of the excitable kind. Each strand acted as a template for a complimentary copy. Those new strands sent out messages, either to break apart or combine other molecules. When no more nucleotides were present inside you, some strands folded on themselves and interacting with the rest of the molecules. Eventually, these ribosomes made more nucleotides and more strands than could fit your doubled inside. Then occurs something extraordinary.
You body split itself into two beings. Inside both membranes were the same molecules as the first you. The same RNA and protein replication occurred as well, and each of those two cells replicated as well to continue making four cells in total. Those four cells grew and divided making another four and kept the process going. Eight cells become sixteen, sixteen become thirty-two, thirty-two become sixty-four, ad Infinitum. Thus was the origin of life.
You kept on evolving in one body, though so have the others. Their genes all increasingly differed between you and each other, until they were their own kind. They scattered themselves to the corners of the ocean, continuing to collectively adapt. While most of your kind stayed in the deep to convert chemicals to sustenance, a select few traveled to the surface and evolved to rely on sunlight, an immensely more efficient power source, to make their food, becoming the cyanobacteria. On the shores and benthic zones, they layered themselves and built microbial mats and stromatolites, mass producing oxygen. We know oxygen to be one of the most crucial requirements of life, but it was toxic to many of the early species. To counteract, a different type of cell evolved to convert the waste products of the photosynthesizers, and make their own waste products which the former happened to use as well. Still you and some more cells simply grew larger than those autotrophs and ate them. There were still many more niches to be filled, and yet another incident resulted in just that.
You were absorbing a respirating bacterium but chose not to digest it. Your expanse and durability made for the smaller microbe's shelter, while it provided free resources for replication.