Literal meaning of the poem is that there is a lobster in world that does not understand the world of humans and lives its life unknowing of it.
Explanation:
The lobster is called 'A shoe with legs,
' in the very first line of the poem and then it is called to be 'a stone dropped from heaven'.
From then on many comparisons are made and it is shown that the lobster is blissfully unaware of the life of humans, their quirks and how they spend their time in their world as it blissfully lives in its life without being bothered.
It is him that also doesn't know that these humans have a completely different idea of him that he has of himself and remains blissfully oblivious until its end.
