Yeah, I think you missed the Ring's true power. In the hands of Sauron, it WAS his source of power. Imagine a Level 20 wizard who has put all his magic powers and spells into a magic ring, so every spell in the game, and while he alone is wielding it, he can cast all those spells without spell components or verbal somatic or anything like that. Oh, and he could cast all those spells as often as he wanted every day with no limits.
That would be like the true power of The One Ring, besides all the things you mentioned.
The whole thing about the ring was that if someone else had it, they had to be powerful enough to take advantage of it and to dominate it. That's why Galadriel feared it, and so did Gandalf. They knew they had the power to fully use it, and it scared them because of just how tempting that was.
Imagine you are a powerful good wizard and all this evil is happening in the world. Then the ring comes along, and you know if you just took it, all the problems you see happening, you could stop them. You are powerful enough to even destroy Sauron with it. Oh, the temptation!
But they knew that the power would corrupt them, and they'd become, in the end, just as bad as Sauron.
