Hi Tony,
You are spot on with your thoughts. In the vast expanse of time (200000+ years of humans and the timescales become larger from there on) and space (the universe and beyond) who we are and what we do don't really matter. But we must still carry on as if we are living fulfilling and validating lives.
I think LC said something to that effect as well although I cannot recall the exact quote. This is a whole discussion that would be best carried out in a bar somewhere over a few beers

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But in the meantime here are some more old Johnny Cash videos, I seem to be having a JC moment.
I Still Miss Someone (with Joni Mitchell)
https://www.youtube.com/watch?v=tVGHamAuD6g
Shame and Scandal on the Family (with Odetta)
https://www.youtube.com/watch?v=uPPVl0kKM1M
Man in Black
https://www.youtube.com/watch?v=t51MHUENlAQ
Pocahontas (Neil Young cover)
https://www.youtube.com/watch?v=XRoGr24KWyo