Based on the current collective consensus, the concept of an 'expansion' is consistent with the redshift/blueshift observations. However this Doppler effect was only meant to measure the rate of 'expansion'. The concept of 'expansion' was first presented as calculation in 1922, which was based on the general theory of relativity. Assuming the agreed upon cosmological principle, it was then inferred that this 'expansion' would exist everywhere; even beyond our observable universe.
That is to say if we were able to travel to where we imagine the CMB boundary is, we would instead find a similar perspective of the universe as from where we view it from Earth. That being said, looking back to our Earth, we would only be able to see this fog of CMB. So there is no real notion of the size of the universe. And we can only guess at how old it is, based on the calculations of Lambda-CDM model.
And all these equations we based on model that does not understand on include the concept of dark energy. For as we all might be able to agree, the existence of baryonic matter only warp the pre-existing fabric of space-time. Take away the positive density matter and you would still have a vessel in which the matter once existed.
So if the 'Big Bang' expansion theory rubs you the wrong way, try thinking of the proposed one dimensional singularity as the pre-existing fabric of space-time without any real matter, rather than a singular point as modeled after a gravitational singularity [liken to a black hole]. Then start unfolding it into existence; first into two dimensional space-time, which is an expansion from our one dimensional space-time, and then into a three dimensional space-time and so on.
I would actually recommend the book, 'The Evolutioning of Creation: Volume 2', where such an alternative perspective of the universe is explored.