Isaac Asimov wrote a whole book about this called The Measure of the Universe in which he takes various familiar measurements and scales them up to the cosmic and down to the infinitesimal.
It’s not about humans specifically, but these are some of the relevant measures:
10[sup]-13[/sup] metres: diameter of the proton
10[sup]-7[/sup] metres: diameter of influenza virus
10[sup]-3[/sup] metres: smallest spider known
10[sup]0[/sup] metres: half the height of tall human male
10[sup]2[/sup] metres: 33-story building
10[sup]4[/sup] metres: slightly more then height of Everest
10[sup]8[/sup] metres: slightly less than diameter of Saturn
10[sup]12[/sup] metres: distance from Sun to halfway between orbits of Jupiter and Saturn
10[sup]16[/sup] metres: one light-year
10[sup]21[/sup] metres: length of Milky Way Galaxy
10[sup]27[/sup] metres: circumference of known universe
Other chapters scale area, volume, mass, time, temperature, speed and so forth up and down.
The fact that we are important to ourselves makes us important, since the OP’er didn’t specify anyone else in terms of judging importance, it can be assumed the importance, in this case, is for us to decide.
If I were the size of the visible universe, my wang would be about 914,000,000 light-years long. As it stands (snork!), we are really, really, really, really, really, really, really, small compared to the universe.
When compared to most other organisms, we are pretty huge. So if you’re feeling like an insignificant speck on a cosmic scale, spare a thought for the enormous biomass of smaller creatures out there.
Yeah.
That’s the kind of thinking that used to steal my sleep. I’ll feel better when we finally find some more people out there. Quaoarans, for example.