I disagree about the value of human life being the main theme, though it certainly is one.
I'd say the main theme of SA is responsibility. Kaladin, and Dalinar's entire arcs revolve around it, and Shallan's is kinda related. One of the reasons Moash is such a good villain is he refuses to take responsibility for his actions. On the other hand Kaladin takes WAY too much responsibility. Dalinar's big moment in Oathbringer is him accepting responsibility for his past misdeeds. And IN WORLD it is confirmed to be a main theme.*
Another major theme is forgiveness, or redemption.
But I like keeping posts short so...
People say something insightful about SA redemption below. ||
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*Kaladin first meets Hoid, or the Wandersail