No. Although there are many overly detailed theories of how galaxies formed in the early Universe, and as a result many questions about how accurate those theories are as new observations come in, the nature of the CMB is not affected by any of those observations or theories. What the CMB represents is a change from the time when the Universe was filled with such a dense, hot gas that it was completely opaque, making it impossible for any light bouncing around between whatever form of matter existed at that time, to a time when as the Universe expanded and as a result became less dense, and therefore became transparent, so that the light being emitted and bounced around prior to that time could finally escape from where it was trapped by its surroundings. In a sense, it's like moving from the interior of a star, where there is so much stuff in the way that it takes hundreds of thousands or millions of years for light to slowly wend its way from the dense central regions to far less dense outer parts of the star. Eventually, when the light reaches the region where the gas is thin enough for the light to escape into space (the star's photosphere), its struggle ends, and it streams outward, throughout the now nearly empty Universe, until (if ever) it runs into something (e.g., the surface of the Earth, where we can see it).

In a similar way, the CMB represents the moment in time when the expansion of the Universe changed it from a dense, opaque gas to a less dense, transparent gas. At that time, the light escaping from a given region was "black body" radiation corresponding to the temperature of the region that it is escaping from (for a discussion of how that works, see part 2 of "Review of Heat Flow inside Stars" at https://cseligman.com/text/stars/heatflowreview.htm#radiative ). As it happens, the temperature of almost the entire Universe was very nearly the same, so the brightness and black-body spectrum of the CMB is almost exactly identical everywhere that we look (because it was still very hot, the radiation was mostly in the far UV; but because it was so long ago, the part of the Universe that we see as the CMB is expanding away from us at nearly the speed of light (or more accurately, it was expanding away from us at that speed at that time), and that has "red-shifted" the primarily far UV and gamma radiation into the microwave radiation that we see as the CMB. But tiny variations in the temperature, greatly exaggerated in maps representing the "appearance" of the CMB (presuming we could actually see microwaves), can show where it was a little hotter and brighter, or a little cooler and fainter. But what are looking at when we look at the CMB is not the light from stars, galaxies, or any other physical "object"; it is the radiation of an almost absolutely uniform, hot, dense (but not quite dense enough to still be opaque) gas, which needed at least a few hundred thousand years after the date corresponding to the CMB to start forming any stars, clusters of stars, galaxies, or any other object distinguishable from other objects. So the theories that are failing to properly explain how the dense, hot, nearly uniform gas turned into physical objects are discussing things that happened (in our sense of time) a long time after the CMB was emitted, and those theories have nothing at all to do with the CMB itself.

Thank you Courtney for your text book response. It caused me to clarify my thinking (and my question) but not to the point that I didn't lose a very long, detailed response to your answer. :-/

The short response to your answer is that it IS text book but there are deep, long-standing problems with the standard model of cosmology:

1. It is dependent on Einstein/Newton gravity being correct. That idea has taken a big blow [ https://charmingscience.com/a-new-study-challenges-newton-and-einsteins-theory-of-gravity/].

2. There is no accounting for "missing" anti-matter but there are ideas that account for it [https://en.wikipedia.org/wiki/Plasma_cosmology] and evidence that this really is a huge problem with the theory

[ https://news.thesci-universe.com/2023/08/for-first-time-scientists-observe.html?m=1 ].

3. There could be big errors in calculating masses at galactic scales [https://charmingscience.com/asteroids-are-hiding-never-seen-elements-from-beyond-the-periodic-table/].

Given the above, don't you think some speculation about alternative explanations are warranted, fun and perhaps even productive? For example, returning to the "root" question, if space-time were curved into a higher dimension, might it possibly create an illusion of an expanding universe, with a beginning? ( Again, a much clearer question. )

Thanks again for your answer, Courtney. It did inspire me to better explain what I'm asking and provides a great summary of the present interpretation of the CMB.

I've reformulated my question to read:

If space-time were curved into a higher dimension, might it possibly create an illusion of an expanding universe, with a beginning?