Re:"We don't even know how life starts"
Um, sorry to disagree, but I recall reading an article in a science mag about how some boffins simulated the theoretical conditions of early Earth, what with atmosphere, pressure and heat, and came away with proof that amino acids resulted from the steam bath.
Knowing that amino acids are the building blocks of life, it is easy to conclude that the conditions for creating life are not so difficult to achieve.
On the other hand, the conditions for survival are much harder, with any number of elements able to radically or catastrophically change the environment to the extent where the fledgling hold that life had crumbles away - until a new batch has a chance to start.
Even then, it is apparently required to be in a relatively stable galatic environment - in a star nursury life has little to no hope of gaining a long-term hold, what with all the thermonuclear ignitions and subsequent violent space winds and cosmic rays that are an everyday condition in those areas.
So, even if we don't have proof, we do have a pretty good idea of how life can start and maintain itself, along with a rather good understanding of how easy the process is. What we don't know, of course, is how often it has actually happened, in what timescale and just how far along it has gone in each case.
Now, think of this : with what we know about the availability of the building blocks of life, combined with what we are learning about the frequency of planetary systems in the star systems around us, well I think it is quite possible that life is positively teeming in every galaxy in the Universe. Of course, most of that life is probably some form of microbial slime, but still, it's a beginning.
And by the time our governments get their act together to finally get humans into space, added to the time it will most probably take us to get there, well let's just say that the slime will have had ample time to evolve into an entirely new something that will really surprise us (right before biting our heads off) !