It's really very weird that anything exists a all.  A lot of people seem to be content to answer the question of why is the universe here with "God created it."  I will allow that is possible, but it begs the question where did God come from?  Is there some sort of even higher powered God that created our God?  And if so where did that God come from?  It quickly becomes a never-ending series of basically the same question.

If you want to leave God out of it you can always go with the scientific explanation that about 14 billion years ago a Big Bang occurred and the universe was born.  That may very well indeed be what happened, but it's still weird because what caused that to happen?  Could be that God caused it, but that leads us right back to the where did God come from question.  Or maybe some previous universe contracted down into a single point and then suddenly expanded again due to some unknown force, but then we're left with the question where did that previous universe come from?

It seems to me there are two options, both of which are extremely weird to think about.  Either there was absolutely nothing and then for no particular reason at all existence just burst out of it.  Or there is no original cause and that "something" be it God, or the universe, or whatever has always existed, which is also a weird thing to think about.  Or probably there's some other explanation that's so far beyond our level of understanding that we can't even conceive of it kind of like how I can't imagine a color that I've never seen.

I know there are other theories like the universe is a dream or a simulation, but that leads to the same sort of question of who's doing the dreaming or simulating and where did they come from?

According to science there was no time or space prior to the big bang so in a way even the concept of "prior" to the big bang is nonsensical because that involves time and there was no time.  I guess if you take out time then there isn't a need for a prior cause, but that's still weird to think about because the only context in which I'm able to understand/perceive existence involves time.  But yeah, time is weird, too.  

All I'm saying is that existence is weird.  For a little while when I was younger that really freaked me out.  It would give me intense feelings of existential dread, but nowadays for the most part I find I can rack my brain about it for a while, still come to the conclusion that it's weird, and then shrug my shoulders and get back to putzing around on the internet or whatever.  I've learned there's not really a satisfactory answer to these questions, there likely will never be one and you just have to kind of accept that.  That's life.  And it's weird.