Why it would not work like that
Almost all of it is shares: about $708.4B in SpaceX and $149.7B in Tesla at the close. To hand out cash he would have to sell, and selling on that scale would drive both share prices down long before he finished, so the real amount per person would be far smaller. Taxes on the sales would take another large share.
What it says about the number
The sum is mainly a way to feel the size of the figure. A fortune that works out at $113 for every person on the planet is still, for one person, more money than most countries produce in a year.
If he kept a billion
Keep $1 billion back and everyone else still gets $113. Keep $100 billion and it is $101 each. The shares are so large that even generous amounts held back barely move the answer.