How we cite our quotes: (Line)
Quote #4
The inheritors of unfulfill'd renown
Rose from their thrones (397-398)
These "inheritors" are dead poets, who apparently occupy a pretty important position in the afterlife. Who wouldn't want to sit on the throne? In Shelley's view, to be a poet is to be royalty, and they should be shown reverence and honor even in the afterlife. We guess poets are shown respect in the afterlife even if they weren't shown any on earth.
Quote #5
And he is gather'd to the kings of thought
Who wag'd contention with their time's decay (430-431)
Now Keats has been "gathered" to the place where the other great poets and thinkers reside in the afterlife. He calls them "kings" again, ones who fought against the "decay" of time. That's what makes them worthy of honor, he thinks.