What is a line by line explanation of "There Will Come Soft Rains" by Sara Teasdale?

Sara Teasdale's "There Will Come Soft Rains" explores the notion of human extinction and the natural world's reaction to the absence of humans. Let's examine the poem line by line, as you requested. The original lines of the poem are bolded and italicized, while my explanation is in plain text.
There will come soft rains and the smell of the ground,
The speaker is setting the scene of the poem's opening by describing the gentle rainfall and the smell of rain rising from the earth.
And swallows circling with their shimmering sound;
Above, small birds fly in circles and chirp happily.
And frogs in the pools, singing at night,
Frogs are singing from their shallow puddles of water.
And wild plum trees in tremulous white,
Plum trees are blossoming with delicate white flowers.
Robins will wear their feathery fire,
Robins still look the same, with bright orange feathers on their chests.
Whistling their whims on a low fence-wire;
The robins are singing on a fence.
And not one will know of the war, not one
Nature--neither plants nor animals--will have any knowledge of war.
Will care at last when it is done.
They won't care when war is over.
Not one would mind, neither bird nor tree,
If mankind perished utterly;
No animal or plant would care that humans have destroyed themselves in battles against other members of the human race.
And Spring herself, when she woke at dawn,
Would scarcely know that we were gone.
Even Spring wouldn't mind that humans have vanished.
 
Essentially, Teasdale is commenting on the destructive, reckless nature of humans and the havoc they wreak upon the planet. Thus, the collapse of humanity here seems to be a good thing for the natural world, as nature will finally be set free from the danger of human life. This poem--like much of Teasdale's work--also alludes to the eternal quality of nature, which trumps mankind's mortality and inevitable doom.