From James Shirley’s Death the Leveller, these lines are voicing the sentiment that prevailed in the Middle Ages and in the Renaissance, that reputation, rank, high birth, etc. are no protection against mortality; one’s earthly rank was no protection against the inevitability. It also feeds off the religious metaphor of “the Whole Armour of God” in which such qualities as humility, good deeds, and honor served as “armour” against the onslaught of damnation. Line by line, a paraphrase might be:
The high status of our noble birth and our rank among people
Are not real, not physical permanent qualities
That will protect us against the fact that we are only flesh and blood;
Death (personified as an icy figure) touches kings like he touches us all.
(The implication being that subservience to the Lord as more important than subservience to royalty, which must also eventually submit to the Will of God after death.) The other verses of the poem (garlands wither, etc.) carry out the same theme: the impermanence of beauty, power, value on earth.