This an interesting question because it depends on how you define exist. The concept of existing is a human invention, and therefore, without us, there would be no such thing as existing. Obviously, though, that is not a satisfactory answer. The real question remains as to whether one must observe something for it to take place. The argument above me points this out quite well. In the experiment of Schrödinger's Cat, the cat is both alive and dead until a human observes it. This is true for many quantum phenomena. In the Double Slit experiment, to prove Heisenberg's Uncertainty Principle, the light acted as both a wave and particle. When humans measured the photons going through the slits, they changed their normal behaviour (from an interference pattern) into two beams of light. Would the universe exist without us? No, because it is (again) our direct observation that interprets the world around us. Without us, there is no temperature, colour, pain or emotion. In a militant solipsist's view, they are the only one's that exist. It is generally well accepted that the universe would not exist without an observer, whether it be a human or alien. David Hume believed the same thing.
God created the universe before he created man. The universe does not need mankind to sustain it. God is perfectly capable of having the universe take care of itself. If anything, mankind has changed what the universe is supposed to represent. If mankind treated the universe the way God intended, it would be a much better place for all of us.
This is somewhat of a philosophical question that requires some arguing of semantics to be able to answer. The universe was created before humans no matter what your believes are. They all agree that the egg came before the chicken so to speak. If humans did not exist, then obviously there would be no one to observe it (that we know about anyway) so in that sense what does it matter if it exists or not. However, I think that it is more likely that there is something else in the universe that can observe what is around them so I think that mankind is not necessary to argue that for an object to be proven to exist there has to be observation.
The universe was not created by humankind. In fact, we wouldn't exist if the universe was not here, not the other way around. It is like saying would gravity exist, if humans were not around. It's obvious that things like specific inventions would not be around if it wasn't for humans, but that's not the wording of the question.
The universe existed for trillions of years before the first human took his first step. Saying the universe is only present for mankind disregards the dinosaurs, animals and all of nature. This question doesn't even consider the billions of other planets that are outside of our line of sight. Mankind is a tiny, insignificant part of a universe that we haven't even read the first page on.
If you think of yourself as your spirit personality which is what you truly are, then you come from the Divine, The One, GOD. You are a part of God, you are the manifestation of God's Love in form. In order for God to be complete not one particle of God could ever disappear or cease to exist for if that were to ever happen then God would no longer be complete and nothing would continue to exist. The whole universe would cease to be. Not even a memory of it ever existing would remain. The Bible says God created us in His own image and likeness...Because we are of God, from God, and for God.
Thank you for reading.
The "concept" and "word" universe would not exist if nobody was there to interpret it, but the phenomenon would still be happening.... If there was a "depends" answer, I would've picked it but...
If I can explain it in a better way, say a randomly super intelligent cat created an object that nobody knew about... The object would exist, but there would be no definition, no concept and no known word to describe this thing.