As James Peebles pointed out in a conference after his Nobel Prize in 2019, the term « Big Bang », which connotes a creation somewhere sometime, is a misleading term.
In the standard cosmological model, Einstein’s equation defines a spacetime exhibiting a singularity (artefact or fact?) , which in the mathematical representation (manifold), is not part of this spacetime .
Interpreting this as a creation of this spacetime is an anthropomorphic nonsense!
A spacetime does not need to be localized in something which would define a time reference and a space container. The phenomenology of the universe can therefore be defined, only, by internal geometric properties of this spacetime.
Thus expansion, for instance, is an internal property: The geodesics followed by the infinitesimal elements of the fluids filling the universe, all emerging from the vicinity of the singularity, diverge. It is an a phenomenology internal of the spacetime.
So, the universe has neither creation, nor past, nor present, nor future and is not expanding, the only sensible problem is that of its existence. Because we are part of this universe and because we exist, the answer is a tautology: The universe exists.
Are singularities artefact or fact of the theory?
One may interpret singularities as limits of the theory or even deffects of the theory.
Obviously, this is possible, but we should not discard that they just reflect the limits of what we may know on the physical world.