IMHO, the key element were 1) foam, 2) warmth. When large bodies of water are formed, wind and earthquakes started to generate waves, waves started to generate

IMHO, the key element were 1) foam, 2) warmth. When large bodies of water are formed, wind and earthquakes started to generate waves, waves started to generate foam from floating organic compounds, and warmth start to generate complex reactions, like in a lava tube. We can see similar things at a shore after a tanker spill. Water-organic foam cells are similar to life cells. In a few cubic km of organic foam, short samples of RNA can be formed just by chance. RNA + RNA transferase can produce copies of itself, forming a primitive virus.