Was not prepared for the philosophical level of this question, ngl.
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Black. While I could say something like "white because it represents all colors and different aspects of life mixed", people have, in reality, completely different experiences from life itself. There are those who know nothing but happiness, or nothing but tragedy, etc.
But what ties everyone together, is the only thing that is certain for us all, death.
Black would represent death, nothingness, the final destiny for everyone alive. Death is what makes life special.
So, IMO, the "end" represented by the colour "black" is what better describes life itself.