These are concepts hard to grasp. For the world around us feels finite. Objects start somewhere and end somewhere. We have a beginning, and will have an ending. Even our universe seems to have begun at some point. Infinity is not a part of our experience, thus hard to believe in and impossible to grasp.
Yet, infinity does support the finite. And we might just be one digit among all possible integers.
The fear of infinity is a form of myopia that destroys the possibility of seeing the actual infinite, even though it in its highest form has created and sustains us, and in its secondary transfinite forms occurs all around us and even inhabits our minds.
So what is everything, in its most literal sense? I believe it is a concept a finite mind could forever contemplate, and never answer. The infinity of everything is not quantifiable. It has no start and no end, neither does it have a largest or smallest. It is an infinity that contains infinities and is contained by infinity itself. It is the endless fabric of everything there is.
If I were to describe it, more than anything else, I believe existence. Everything. Is potential. The potential for everything to exist and everything to be. A potential that is fact. Endless potential for our and countless other realities to exist.
Everything is because nothing is not. Endless realities being just one of the many effects of existence itself.