Those three were not gods and nowhere near them before they acquired their power from the Heart of Lorkhan, powerful yes, but gods, not even close. Dagoth Ur, was not a god when you kill him. You couldn't kill him at all. You can beat him but his god powers just resurrect him and he start unleashing against you again. There is a difference between killing a god and being able to defeat one. Gods are fallible too, you can be more skilled in fighting than them but they just heal quickly and continue to fight you. Eventually you are going to wear down and die. Thus is why when you struck down Dagoth Ur you had to hurry and destroy the heart before his power resurrected him the god state.
That entirely depends upon your choice of how to view things. Did the Tribunal simply plug into a God's heart like an electric socket and become fascinating but drab little light-up toys? Or did their tampering with the Space-God's heart, so linked as he is to the Time-God, create something altogether more?
Varieties of Faith clearly states that from the view point of the in-game writer that they must be anologous of each other just because Alduin is a dragon and Akatosh is a dragon, all he is doing is drawing lines, it's also been stated that in-game writers that write from their point of view can be incorrect and thus is what makes the lore more believable that people can get it wrong from their point of view. Many things that you and other people link as proof (such as both links in your sig) are not lore, they are just random writings by Michael Kirkbride, nothing more.
Yes, in-game sources can be wrong.
That said, when every possible in-game race has their own creation myth that echoes of all the other, their own pantheon that echoes of all the others, and the pantheon's attributes that echo of all the others, you become hard-pressed in asserting that they are dubitable.
Things are dubitable when there are key and vital interpretations to the contrary that are presented in the world. For instance, if there had only been one version of the Battle of Red Mountain present in Morrowind, we would have little to no reason whatsoever to question the veracity of it. It's not until the other interpretations are put alongside that an act of interpretation and doubt begins.
I challenge you to assume the burden of proof and demonstrate to me that Alduin is in fact NOT Akatosh.
More on Kirkbride at the bottom.
Still doesn't make a difference of you need a constant source of power to be able to fly. The magical reaction between the ingredients could be causing the constant output of magic needed to fly until the reaction stops outputting magic.
So if I were to have a vast number of these potions, since we assume that they are more than possible to make, I would essentially have significantly-long-lasting levitation, no? Should we remove them from the world so I can't stock up on "OP" levitation potions?
This just shows that your perception of the events of TES are blown out of proportion. You (and others in the lore community) see everything beyond what they truly are and make it into high fantasy when it is really just at a normal level. You use subgradient of gods to act like things have a hidden potential that can be unlocked at will to gain a variable amount of power when this is just thinking too highly of a more simple event. Nirn is made of etada and the powers of the eight divines. Lorkhan's body makes up the two moons of Nirn and the stars are the holes of the spirits that left mundus through Oblivion to Aetherius before they lost their powers and immortality and become chained to Mundus like the eight divines and other etada did. Then of course the Sun is a huge hole ripped in Oblivion from the retreat of Magnus from Mundus. The Dwemer believed that they could bring Lorkhan back to like and that he would give them immortality, that's it, it wasn't some subgradient where they had some hidden potential. The tribunal tampered with the Heart of Lorkhan and siphoned off the power of Lorkhan that laid within because they were greedy and wished for godhood, once again, has nothing to do with "subgradient", just greed and direct power of Lorkhan. The Apotheosis of Tiber Septim was the only thing that could be accepted of sub-gradient and needs more back information to really flesh it out. Shattering of time by the monkey prophet is once again taking things too far and literal, it's just a tale from a mortals perspective. The concept of the wheel and the "I" is once again just a random writing that is not lore. The Yokudans cutting the atomos is also just an obscure story that has no semblance of truth behind it.
In the end, every world has laws of reality and being able to fly everywhere at will is not within those laws for a mortal with very limited magicka.
This also shows that your perception of the events of TES are selective in nature.
Most everything that is present in the obscure texts can be unpacked and determined through in-game work. Most notably in the 36 Lessons, though no doubt you'll dismiss that too as the ravings of a mad Dunmer that have nothing of value contained within. I find it interesting that you're willing to accept Tiber/Zurin/Wulfarth's apotheosis as a raw example of the existence of these concepts, yet you still deny them elsewhere as 'just mortal perspective,' or 'imagining too much.'
There's not much in the way of arguing this, either. If you truly think that MK's writings, in or out, have absolutely no ties whatsoever to the world, considering the man founded its metaphysics as an in-game writer, then all I can say is that your view of TES is a deprived one, and one that deserves some much-needed re-anolysis.
But even if you insist to hold to it, at least I can say that my interpretive world is by no means boring, limited, and full of negation.
Since we now essentially have to argue which choice is right and why, we might as well hold off or create a new thread, seeing as that's a much broader topic than what this thread is intended for.
But at the very least, recognize that if my view is an interpretive choice, then yours is just as well.