I did have a go at this in a previous post addressed to nine lives.
The physical universe is a very small part of a metaphysical universe. It is not the case that matter is the only thing that is real, forces and spiritual dimensions are also real.
There is a sphere of influence in which the tiny physical universe was formed. The metaphysical universe had no beginning. All the matter in the universe had no beginning because something can not come into existence out of nothingness. Even so-called God needs something so that it might be advanced into structure and life.
The universe can be considered to have a beginning inside the metaphysical universe when a single type pre-matter substance was acted upon, perhaps by the introduction of the 4 known forces. Perhaps hydrogen atoms formed and under the influence of gravity and an unknown force that caused spacial expansion or inflation, gravity and the forces of cohesion constructed our universe.
There can never be a finite answer to questions that deal with the infinite.
All we can surmise is that a non-physical universe has existed without a beginning. Within this non-physical universe some form of pre-matter existed. It may have been subatomic or energy. Whatever it was it was all of one substance. The 4 known forces were introduced and subatomic connections produced the first atoms of hydrogen. Gravity and the passage of what we call time enabled nuclear fusion to process hydrogen into helium and so on and so on until all the necessary building blocks of the physical universal structures and life were created. An unknown force of inflation and rotational motion was added to the mix to hold the universe together in a gravitational, centripetal waltz.
Life itself was then added and Twin Turbo and wafflehead crawled from the primordial slime.
The process that built the universe and added complexity to the first life-form seed is divine, creative evolution.
All mater was created from a single substance as seen by the periodic table and all life was created from a single organism as seen by DNA.
or, you could believe that Genesis is a literal account of creation in which case you have no more questions.
