And, as you observed, all that multi-verse physical cosmologies accomplish is moving the goalpost backwards in time. Legerdemain does not explain why this instead of nothing at all.
In the absence of space, things cannot exist.
Both space and time are required for physical causation.
Penrose's physical cosmology is "open" - he takes space/time, inertia, physical causation and information as "given" when in fact no one can say that the physical laws and mathematics of this universe would apply to any hypothetical prior universe.
Truly, the only "closed" cosmology known to me is Max Tegmark's Level IV Parallel Universe (radical Platonism) which posits that everything in 4D is a manifestation of mathematical structures which actually do exist beyond space and time.
Scriptures speak to a similar manifesting of reality. Logos which is translated "Word" is also the root of the word "logic:"
It seems to me the entire point of "eternal universe" cosmologies is the avoidance of the notion of a real beginning of the universe. And yet the Big Bang clearly indicates such a beginning. The strategy then is to say that this beginning is not unique, that "beginnings" (and "endings") of world systems go on cyclically, forever, in time that itself has no beginning or end. Time is simply posited as being "there" eternally, a sort of matrix in which events can happen. Time itself has no beginning (first cause) nor end.
The funny thing is science fundamentally is devoted to the elucidation of causes of natural phenomena. Why is it acceptable for science to turn a blind eye when it comes to the cause or origin of time itself?
Instead, as you say dearest sister in Christ, they keep moving "the goalpost backwards" along an infinite causal regress that doesn't "bottom out" anywhere. I.e., there is no first cause. But if there is no first cause, then how can anything come to be what it is? Penrose himself tells us that our universe had initial conditions of extremely low entropy. How could that be the result of an infinite random process?
Questions, questions....
Thank you ever so much for your insightful essay/post and for your kind words of support.