Gravity does not "originate in a curved space-time".
Gravity is a curvature of space-time. Closely associated with, and easily predicted by, and entirely calculable using the amount of mass that is nearby. That is what Einstein said (in grossly layman's terms). You are trying to set up an origins debate where there is no origins debate.
If you want to find the true origin of gravity then you are headed in entirely the wrong direction if you ask Einstein (or even Newton for that matter). You need instead to look to quantum mechanics. Please don't ask me to explain it to you because 1) the jury is still out, 2) the math is really hard, and 3) I don't understand it myself.