What Really caused the CMBR?

The most distant image that we have of the Universe is an image taken by a satelite called WMAP.

The image is of what is called the last scattering surface of the cosmic microwave background radiation or CMBR.
This 'snapshot' is at a distance of just under 13.5 billion lightyears away.
It is an image of the first 'light' of the Universe.
The CMBR accounts for 99% of all the photons in the Universe.

All the light, heat, and other electromagnetic waves from all the stars and galaxies out there, make up the remaining one percent.

We are unable to see beyond this image of the CMBR, and yet all the processes described by the Inflationary Big Bang theory are described to have taken place beyond or 'behind' this image.

Inflation, the Big Bang, the baryogenesis that was somehow responsible for the existence ordinary matter, the nucleosynthesis of primordial helium nuclei and finally, the manufacture of the first neutral atoms of hydrogen and helium, all took place beyond the CMBR's last scattering surface.

The photons we observe in the WMAP image are the first photons that were free to travel, unhindered, throughout the Universe, and as mentioned, that light, that appears in every direction has taken more than thirteen billion years to reach us.

When the photons first left the final scattering surface, they were quite cool by cosmic standards.
The surface of the Sun is about 5500 degrees, while the photons. Of the CMBR's last scattering surface photons were about 3000 degrees when they were first sent on their way. That is all we really can tell about them.

What all this really means is that anything could have happened to cause the exitence of the cosmic microwave background radiation.

It does not mean or prove that the events as described by the Big Bang theory actually took place as many physicists will have us believe.

What do you think caused the cosmic microwaave background radiation?