The Illusion of Causality

What makes me “come back down” when I jump?  Answer: gravity.  Every elementary school student knows this.  But what if the earth was not rotating?  What if I was lighter than air?  What if the earth was the size of my back yard?  I would not come back down.  An obvious and perhaps pointless digression, all for the purpose of reminding me that there is never a single “cause” of anything.  Every single interaction in spacetime is effected by a causal chain that runs from the quantum scale to the cosmological scale.  Every time you ever hear an action (or reaction) attributed to single cause, you can rest assured that an infinite regression of causality and contingency has been left out of the explanation.  If the universe we observe is this seeming-infinite interconnected network “causal” interactions regressing back in time, why do we assume (or expect) we’ll find a single cause for time-space, or the existence of our universe at the beginning of it all?