Sort of a complicated question, I'll try to ask. How was I born me and not another?

[EruptedCarcassBloat]

Lmao, okay, first of all. The food that we eat is what makes up our body. Without food we would shrivel up and die.

True, but irrelevant.  You aren't actually what you eat, that's just a poetic flourish that refers to a more complicated subject.  

So yes, our body is able to transmogrify edible matter into the necessary components to create a baby. Therefor babies do come from hamburgers. 

Transmogrify, lol...is that the technical term?  Sorry, babies don;t come from hambnurgers.  Don;t take my word for it, though.  Sit a hamburger on the table and watch it...wait for a baby to come out.  Report your findings

I really don't think you understand this any better than I do, from what I can see. And yeah, my parents made me, okay.

Which answers the question of why you're a human being as opposed to a rock, or a bat, or what-have-you.  

But there was a lot of other matter in the universe that didn't happen to become my parents, it just became inanimate objects.

Why would that be relevant to you, since we've established that you came from your parents...and they were, in fact, human beings?

I wonder all the time why I came into existence and am not just an unconscious part of the other vast majority of matter that makes up the cosmos.

If things were different things would be different.  In your case, the conditions from which you arose lead, inexorably, to your being a human being.  Had your parents been a seal...you'd be a seal.

This conversation isn't nearly as informative and scientific as I was hoping it would be :/