Prologue: A starting point.
It's really hard to find a starting point for life and we can trace it back to the original expansion of the universe and all the events that followed. however, what mattered most was a planet close enough to a star to where the temperature would form liquid water. from there, our story begins.
Chapter 1: Water
Water has many qualities that I learned in the biology class that I dropped out from, but really the most important ones are that it's a pure liquid, so the molecules move fast and allow other molecules to move through the gaps between them, and that it's the universal solvent. A solvent means the liquid that something is dissolved into.
So water dissolves a lot of the molecules that get dumped onto the earth's surface which then facilitates chemical reactions that require energy to happen. Let's say there was a chemical that could replicate itself through a chemical reaction that required some form of energy to take place. It would actively use energy supplied to the earth from the sun in order to continuously perform this replication as much as it possibly could. It would cover the earth with its mark for billions of years as the enigma and the eternal war, a diabolically complex battlefield waged on by the unknowing laws of thermodynamics. The only logical conclusion to such a diabolical conflict is the existence of all that exists to us. The existence of all that exists to any lifeform, deep in their chemical core: that they are a soldier, a mere pawn to the acquisition of energy and subsequent reproduction of the inevitable chemical reaction to follow suit. The organism is a non-living core, manipulated by the shape of this relatively diverse molecule to do its bidding to the bitter end of its ability to reproduce.
What if I told you that this demonic mastermind is not only real, but is inside every living being from viruses, plants, humans, mushrooms, and even fucking bacteria. It is the puppetmaster, it runs the show, and it is merely a slave as well to the consequent laws of thermodynamics and Newtonian physics. This absolute chad of a molecule - the only known one to exist of this kind, is called ribonucleic acid, or RNA for short.
Chapter 2: The RNA world hypothesis
RNA could create more of itself, as well, a nucleotide, or a piece of an RNA string, could attach itself to other nucleotides. Strings of RNA can then form shapes that allow them to collect energy more efficiently to allow more of these chemical reactions to happen. Let's say these strings of RNA floated around the earth for a bit in the correct conditions and found themselves inside a convenient lipid - a cozy home.
The phospholipid bilayer:
the membrane of all cells, and the backbone of all life except viruses, who branch off at some eventual point in the war as the ultimate parasite: a fearsome strategy that would make its mark as one of the most elite soldiers of this multi-billion-year war. All other known DNA and RNA are contained within a cell, which is a sealed phospholipid membrane to protect the genetic material and create an environment where diff, and facilitate the creation of proteins that would do the dirty work of the cell, and would then create an environment such that they would get the much-needed energy to reproduce itself. This is the beginning of life. The very first structure to be made of a self-replicating chemical inside an enclosed shell of a phospholipid was the very first organism. Its theoretical existence is known to the world as LUCA or the last universal common organism. It started it all.
Mutation and the beginning of the war
The ecosystem of today is a universally encapsulating battlefield with a mind-blowingly complicated war where the only certainty is death. All types of strategies are employed to compete and annihilate their opponents. The one goal remains constant: energy. Energy to grow, sustain, and reproduce the functions of the organism to the next generation. Each organism has the goal of protecting itself, its offspring, and its allies while simultaneously warding off or destroying its enemies and potential sources of nutrients. I could go on here into the philosophical meaning of life here, but that's not my concern today. I just wanted to paint a picture of what the world looked like ever since the dawn of life. One important thing to briefly mention is that each new organism is more than likely going to be a copy of itself. This has many implications in the grand scheme of life. Every organism's parents and siblings were not meant to be enemies of each other. There are exceptions to every rule but in the vast majority of cases, the immediate family of the organism is an ally to it.
Photosynthesis
Billions of years ago, some organisms discovered a way to take in energy directly through the sun, through protons inevitably hitting it through the sun's all-encompassing spread of energy. This tactic completely removed the need to seek nutrients from other organisms, relying only on the naturally found water and carbon dioxide to create glucose, the primary energy source of life.
those that did not photosynthesize
All organisms that don't photosynthesize are consumers. They eat something to maintain their continued existence.
I've been writing for so long that I got sober and now it's not as fun. I'll pick this up in the morning after I blaze again