I ask myself two questions.
First how do you define the first existence. Humans define the beginning of existence through the omnificent being god. Even so, is that really sufficient? This begs the question where did god come from. The chicken and the egg paradox if you will.
Second, people say their was nothing and then the big bang/god created the universe. What is nothing? Is it the color white or maybe black? Is is the existence of no intelligence or physical objects? I don't think "nothing" can be defined. Something will always encounter a space whether it's a single color, air, or whatever. What is the "nothing" the universe expanded from? I tend to think that humans can't understand and need a higher plan of thinking to interpret the answer.
That's my abstract thinking for tonight.