Other planets are not going to have the same atmosphere as ours. Chances are we're not going to be able to breath on these planets.
Mathematical nonsense.
There are hundreds of billions of stars in this galaxy alone, with hundreds of billions of galaxies.
Each star has multiple planets.
Eventually, we will find some that support our life.
If i am not mistaken astronomy reached that goal already to find some planets that looks similar to earth that can support living.
So indeed there are really planets which can support human lives. The only problem for now is the tool for transfering humans from the other planets since those planets are a million light years away from the earth.
Hmmm....
The detection of planets in "habitable zones" is a far cry from habitable planets. But maybe 1/1000 of these would in fact be suitable.
So then the only problem is that it would take five million years to get there.
So you see, it is not possible for humans to find other habitable worlds. But it is possible for the evolutionary processes of life to be spread.