In the grand scheme of things, a human lifespan is in the same ballpark as a Planck instant when considering an infinite universe. That doesn't mean either are insignificant in their own context though.

Time can be infinitely subdivided For all we know, billions of entire universes could be created and destroyed within ours in an instant. Our own universe could be as insignificant as an atom in some higher level universe. We can't know that. But what I do know, is that I exist in this moment, and that's enough for me.

Slightly related is the anthropic principle, or the "observation selection effect", which is nicely summarized by this analogy:

This is rather as if you imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!' This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, frantically hanging on to the notion that everything's going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.

• Douglas Adams, The Salmon of Doubt

The takeaway I get from this is that it's important to appreciate the time we have, since everything comes to an end eventually.