I don't think there are other humans out there (because that would be really freaky because evolution and natural selection are meant to be random) but I think the chance of life being out there somewhere is quite high.
A few decades ago they created conditions similar to those of the early earth (no free oxygen and the basic compounds e.g. water, hydrogen, carbon etc.) in a sealed container surrounded by a vacuumm so that nothing could get in, like bacteria, and they were amazed to find tipical organic compounds formed crutial to life (amino acids - needed for dna).
So if there is a planet out there with an atmosphere similar to ours the chance of life arising there is very high.
