Interesting post/thoughts, Mismused, I commend you.
Modern science is amazing and I use it to muddy, just slightly, the clear pond of epiphany you are emphasizing.
'Snowball Earth' is a recent theory, one with rather substantial proof, that states the entire earth was covered by thick ice, from both poles to the equator and yet life survived.
'Life' has also been discovered deep in the ocean around volcanic vents, in boiling toxic water without the prompt of photosynthesis, (light), which challenges the concept that 'light' is the mother of life.
But there is another, more tenuous thread in your post that I interpret in friendly terms, at least according to my understanding of life, evolution and the universe in general, and that is the innate desire of life to survive under any circumstances.
I do not discount at all the primacy of 'light' as entirely essential to life, it is indeed but it is also a form of energy and thus derivative, not fundamental, by definition.
That innate, 'will to survive' innate in each cell of life, regardless of form, can be extended to the travails of mankind with conflict and war and competition, on all levels, from the mating urge to an economic system, that nurtures the individual life form to survive against all odds...