Just because something is stable and steady today it doesn't follow that it was always that way.
Think of striking a match. When you do so the chemical properties cause the light and heat to flare greatly, before settling down to a steady, relatively stable flame.
If your perspective was limited only to a tiny portion of the time when the flame was steady and stable, would you be correct in your assumption that it was always the way you have observed it?
I admit measurements of the present make no strong statement about the past, however, within your analogy the flame of a match, after settling down, fluctuates an awful lot on the scale of 10^-15 of its total heat output. But the speed of light does not. Not only would you have to come up with a lot of wild physics to allow c to vary by many orders of magnitude over 6000 y, you’d also have to come up with a mechanism to get it to chill out to the tune of .000000000000001 or less after these quite wild changes. Good luck!
You would be if the flame behaved exactly in every way like a photon. If the flame doesn’t then what is the basis for the comparison?
You keep evading the question? You are proposing that the laws of physics governing photons are not absolutes. the Onus is on you to prove it and not on others to prove a negative. This is simple logic.
You will question everything except the story of the creation. Do you mean that the laws of physics are mutable but the arbitrary claims of genesis are not?