Whilst intelligent life would be EXTREMELY rare, I think that the chance of intelligent extra terrestrials existing is not just high, it's certain. Will we come into contact with them? Not in the near future, not by a long shot.
Furthermore, we are a (as we would define) type zero civilisation, and the lack of evidence (read Fermi paradox) that civilisations beyond our point seems to suggest that no alien civilisation makes it much further past our point.
However, I also believe that any alien civilisation that has advanced beyond our point would not communicate in the same way we would (mostly via some form of electromagnetism); they would use other means that would not be subject to noise such as nearby stars, or perhaps they have even figured out faster than light communication. So perhaps the lack of evidence also suggests that aliens would largely be far more advanced than us.
So you can either say two things, aliens are either far more advanced than us to the point when we can't actually detect them, or alien civilisations are self destructive and don't advance much further than us. Make of it what you will.
Can I cite the Drake equation? The Drake equation states that:
N = R* x fp x ne x fl x fi x fc x L
where:
N = the number of civilizations in our galaxy with which communication might be possible;
R* = the average rate of star formation per year in our galaxy
fp = the fraction of those stars that have planets
ne = the average number of planets that can potentially support life per star that has planets
fℓ = the fraction of the above that actually go on to develop life at some point
fi = the fraction of the above that actually go on to develop intelligent life
fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L = the length of time such civilizations release detectable signals into space.
It is used for working out the probability of ever coming into contact with aliens. However, as you can tell, a lot of the values are basically just big question marks right now.
As for regular single cell life, yeah, I bet that is everywhere, in almost every galaxy with planets.
