Mortality can be a tough thing to accept. But, if it helps, just know that it is always a spectrum - it is never binary - in that everything has an end (as far as we, and our physical/cosmological models, can understand).

We've got it better than pretty much every other type of animal life on earth (with a few exceptions) - insects or our pets, for example - so while we might not have "cosmological endurance", let's call it, we've still got it pretty good. :)

Agreed that it's a shame we can't explore everything, though!