There are around 200 million stars in the Milky Way at the least. There are around 200 billion galaxies in the Universe at the least. Thus, there are 40 quintillion stars in the Universe at the least, each possibly containing life.
The probability of other life in the universe keeps falling. Before any exo-planets were discovered, the probability of life on a planet was 1/9 (we have not discovered life on any other planets). As we discover more exo-planets (and don't find life) the probability declines - now approx 1/3700.
no primate on this space rock/et-ship can quite comprehend infinite space. Everything you can imagine is out there, just not likely to cross paths. It wasn't that long ago the churches were burning people for saying earth does not revolve around the sun. Infinite!
There is no proof everything we can imagine is out there. Unless the universe is infinite(which we have no strong evidence for) just because I can imagine a planet of lusty catgirls does not imply the existence of a planet of lusty catgirls.