Here’s something I realized a couple of decades ago, and I sometimes wish there was a better way to communicate:
When you think of people (or animals, plants, whatever)( that were alive when we were kids, but are not alive in 2018 (when I’m typing this) — the fact is that they are alive and well in their segment of the space-time continuum, during the duration of their “lives.”
They may not be alive “now,” but what is “now” anyway? Nothing at all makes this (passing) instant, “now,” unique, or more real than any other moment; it’s just the moment we’re currently aware of, or “experiencing”. What we think of as the “past” hasn’t gone anywhere; it’s not just not the moment we’re currently perceiving.
I came to this realization after reading Einstein’s writings. I was happy to later find an interview in which Einstein was asked if he mourned friends who were no longer alive. He said of course not — and that anyone who understood the nature of space-time wouldn’t, either. They were still completely alive in what we think of as the “past.” The notion that the present “instant” is the only “real” one is just silliness.
What it comes down to is that the past is just as real as the present, it’s just located in a different part of the continuum. The future, whatever events it contains, is also just as real as the present. If you read these paragraphs, you just read them in what is now your “past” — but it’s just as real as your present, after you’ve finished reading them.
From this point of view, the dinosaurs haven’t gone anywhere; they’re just in a different part of the continuum. People who “were” living 500 years ago “are” living 500 years ago. Whatever’s going to happen in the future, already is happening in the future.