didn't invite many people to his party
Subordinate means someone who is of lower rank in a job. So the manager spoke to someone in a lower rank than him in a cordial tone.
The only sound heard is an icy whisper
imagery is a figurative illustration, where you can imagine it happening in your mind
like: see/feel/smell/hear.
These lines demonstrate the political activism of his poetry because it goes to show his perspective on America, while also protesting against American racism which was almost at its peak at the time he wrote this poem
