I feel like one should already have this understanding of cosmic insignificance from multiple kinds of knowledge that I remember encountering in grade school.

Just looking up and knowing those are not just stars but full galaxies. Learning a little about geological time spans versus paleontology versus written human history. From those, it should be obvious already just how ephemeral our lives are in time and space.

I got another (fractal?) feeling of insignificance when I realized "ancient" poets, philosophers, and historians were describing basically the same emotional and metaphysical concerns that we grapple with today. We cram some extra modern knowledge into our heads, but the fundamental cognitive life isn't really changing much.