Hmmm... Let's see! Without the sun all living thing on earth would die. The plants need the sunlight to make food, the herbivores eat the plants, and carnivores eat the herbivores. The plankton in the oceans need sunlight which are food for the fish and whales. Because we came from the star, we still need the star to survive.
Without the universe the star couldn't have existed. The universe was created first so what matters that was left after the big bang could behave certain way according to the law of physics in this universe.
I don't know how to explain to you fully, but everything is interconnected, even the life on this earth. they all depends on each other for survival. The atoms is made of electrons, protons and neutrons...without them you wouldn't have atoms.
Well, of course, it's all connected.... nothing in the universe happens
ex nihlo... the problem with questions that start like that is that you're asking the wrong question. What it sounds like you're getting at is whether the universe is self-contained, or if there was something else, the philisophical Prime Mover or Divine Watchmaker, that started/maintains the machine, so to speak, which would be the source of any 'meaning' you wish to ascribe to the universe, or if the whole process was entirely self-contained, self-creating, and thus, has no greater meaning, just a marvelous, beautiful coincidence that we're fortunate enough to exist within...
Personally, I prefer the latter, as it allows us to create our own meaning as far as what the universe means for us, which, to me, makes it much more valuable and precious than feeling like a pawn or drone in some ineffable creator's plan...