I don’t believe that we are alone in the universe.I have never thought was true.
I cannot offer anything that would be accepted as a proven truth, I am simply going by my personal opinion and belief.
If could be that since earth is known primarily as a Warrior Planet. most entities keep several light years of distance between us and them, give or take occasional observations of us. and how close we are to deliberate self destruction.
And how do you know that other life forms are peaceful?