Joint Chiefs of the Imperial Military Rank confusion

This question I suppose is really more for understanding the in-universe explanation around the rank plaques in a New Hope and how they fit with the larger Star Wars universe.

In a New Hope, when Grand Moff Tarkin tells the group of officers about the Imperial Senate's dissolution, these aren't Tarkin's lackies so to speak, they are the Joint Chiefs of the Imperial Military consisting of General Hurst Romodi, General Trech Molock, Rear Admiral Conan Antonio Motti, Chief of the Imperial Navy, Brigadier General Moradmin Bast, General Cassio Tagge, Chief of the Imperial Army and Senior Colonel Wullf Yularen.

My question is, Star Wars retrospective lore wise, if these guys are meant to be the joint leadership of the Imperial Military then why are they so low ranked compared to others?

If Rear Admiral Conan Antonio Motti (who has a severe lack of faith in the force) is the Chief of the Imperial Navy and he is only a Rear Admiral where does that put him with vice, full, fleet or grand admirals who are supposed to outrank rear admirals? Would he outrank Thrawn if Thrawn was still around at this point.

Cassio Tagge eventaully becomes Grand General but why isn't he a Grand General now if he's meant to be Chief of the Imperial Army?

And Senior Colonel Wullf Yularen, throughout Andor, is made out to be the highest ranked member of the ISB which would make sense as to why he is Chief of Intelligence on the council. But then why is he only a senior Colonel. As I understand, the reason that Krennic got a fancy cape and a full director plaque is that he was the Director of the Imperial Military Department of Advanced Weapons Research within the ISB, while Colonel Yularen was in charge of the ISB at large.

Still point of uniform decorations are to represent superiroity, so shouldn't the Joint Chiefs have higher ranks and bigger rank plaques?

I understand that most of the higher ranks weren't invented when New Hope was made, but what is the in-universe reason for this?