We dont know.
We dont even know the chances. We have two variables that we know

1. We exist.
2. We know of no other life beyond Earth.
   Beyond this everything is suppositions and guesses. We may be a 1 in 100 trillion fluke.
   We may be in a Universe teaming with life we cannot see.
   Every other answer to this is loaded with assumptions, many of them assumptions in fields the assumer does not understand.
   The answer to your question is that it is a deep question, a deep one that requires huge amounts of science to be done on.
   The only solution will be for us to roll up our sleeves and work hard across many fields.