Did you know that a marble is about half the size between the earth an an atom? Think about that shit.
And there were theories about atomic structure that it resembled the solar system with the sun being the proton and the planets being electrons but this is not the case.
There is a law of scale and many other factors that have ruled out this possibility. So the idea that each cell or atom contains a universe, though elegant, is probably incorrect.
There have also been studies done, based on what we know about life, that have predicted how many advanced civilizations there are in the universe and it is very small percentage of planets. Many criteria must be met, must have water, must be correct distance from sun, must be shielded by large near by planets, must be correct spot in the universe, must have circular orbit as opposed to elliptical orbit. The list goes on and turns out our solar system and planet combo is extremely rare in the universe. That being said the shear size of the universe yields the statistical possibility that there must be intelligent life out there. This I can say for sure beyond a statistical doubt. However again remember that out of our planets 6 billion year we have been here for 1 million if you are extremely generous on what you call intelligent life. That is like 4 days of your life if you live to be 80 years old. All of human evolution, wars, poems, everything taking place in 2 days of your life.
So There is intelligent life out there but even if there is the universe is so vast, and on such a large time scale that the possibility of a class 3 civilization, if they even give a shit about us, coming into contact with us, when we exist, for the 2 days of life, out on the edge of the universe, with nothing to offer... That's what makes me sad. If that makes any sense...
So yes, we are small, insignificant, lack the ability to comprehend our size, and even by our own planets standards we are pretty unsuccessful. But what are you going to do, tomorrow you will wake up, and once again your world will revolve around you.