I think fermentation and radioactive beaches are my favorites. From a thematic perspective, I don't have the brains to actually have an opinion on whats most likely or correct.
Fermentation is funny & resonates with how fermentation is the most important chemical process to civilization
Radioactive beaches are nice if we ever manage to destroy all life in thermonuclear war, dust to dust, radioactive beaches to radioactive beaches.
edit: Creation Myths are acceptable
Lipids form spheres around hydrothermal vents deep under ocean, convection makes them cycle near hot areas to cold. In these cycles, larger bubbles tend to absorb lipids from smaller and at a point they split. They "eat" and "reproduce".
Small organic molecules can penetrate the lipid layer. Near a hot spot tons of molecules come in and then react to form long chains. These chains are too large to pass through the lipids. A gradiant of concentration of molecules inside a lipid bubble induces these bubbles to draw more lipids from smaller molecules. We now have natural selection and competition, make the biggest chains. Then enzymes, proteins and information can be encoded and were off to the races.