Ill started with hydrogen that got compressed into heavier elements within the stars who then exploded and become heavier stars who then exploded etc. Consider that the universe is dated at about 15 billion years old so there was plenty of time for stuff to form.
You can say everything that the earth & nearby planets started off with comes from the stars.
How did the hydrogen get there in the first place is something ppl are trying to figure out. We can get very close in time to the moment of the big bang, but as to why it even happened in the first place is not known currently
Answers were supposed to be forthcoming with the big hadron collider in Geneva but thats still under repairs and won't be up & running till Feb i think. It won't really start pushing the limits for at least a cpl more years yet till they can get it stable.
I'm not sure if the universe is finite i understand that it is expanding. That galaxies are actually drifting away from each other with speed.
Perhaps but what are the chances that it could not happen amongst hundreds of billions of stars within our own galaxy let alone the other billions of galaxies with their individual billions of stars out there
The distances are so vast between these galaxies that light itself might take thousands if not millions of years to cover the distance between.
Its all big bang, but we dont know the why or the how (yet), all we know is when it happened.
If you get a chance try to get hold of Stephen Hawkings
A briefer history of time