This is such a good question! I'm looking forward to seeing what others say. I think that we are alone in the universe. I once read that the requirements for life to evolve on earth were unique to make it almost impossible to occur elsewhere in the Universe., The right kind of Sun, The right size of planet and distance from the Sun, The planet's environment. & etc.. Sorry I can't remember it all now.
People ask what came before the Big Bang. I say another Big Bang. It starts with the Big Bang, the Universe expands and reaches a certain point and then because of the Law of Gravity starts to recede. And the process begins all over again.
But scientists say that the Universe is still expanding. 15 billion years! But what if it continues to expand and breakdown and not recede? There might not be another Big Bang and this is it?