If you start with Null, absolute Nothing, then there is no space, time or, most importantly, Rules.
Absent Rules, Anything can happen.
From this Existence forms, each in isolation from the others.
Every possible universe forms in the infinite and eternal Null, including those far beyond our ability to comprehend or classify.
In Null EVERYTHING happens eventually.
From this our universe and an infinite number that appear identical to this "point in time" exist, indistinguishable until thier point of differentiation.
These universes have the appearance of being alternative timelines when in fact they were never connected to our universe in any fashion and were always independent.
This illusion appears to be the point of issue here....
(Side note: there are infinite variations that appear the same to the end with the only differences being things like whether a non-interventionist deity actually created that copy or if it's a spontaneous generation or the result of another universes actions etc. They can't be differentiated by any internal observer, and often not by external ones, yet they are unique and separate.)
(Side note 2: Quantum particles appear to be a manifestation of the indeterminate differentiation, as we cannot know "which universe" we exist in until the spin of the particle is observed etc.
In essence, scientific study reduces the probability space in which the observers exist within, limiting the range of universes which they can now occupy.)
And yes, this is just some shit I came up with and it's semi-religious in nature, as a means to "answer" the "reason for life" while being reconciled with the scientific facts established.... I'm pretty sure I'm wrong somehow about some part.