Ridpath's poem is about the sting of being treated as invisible. It opens with one blunt line: "You looked right through me." Someone has failed to really see the speaker, and that single sentence carries the hurt.
What follows is a kind of defensive shrug. "I was beneath you or so the story goes" suggests the speaker is repeating how the other person sees things, and the "or so" hints they don't fully accept it. Then comes "You're nothing special so I go home," which sounds like the speaker turning the insult around, or trying to talk themselves out of caring. Going home feels like retreat, but also like a choice.
The final line, "Pleading ignorance to another lost soul," is the trickiest. The speaker seems to dodge or deflect, perhaps even doing to someone else what was done to them. The mood is quiet, bitter and tired, with a lingering loneliness. The short lines leave a lot unsaid, which makes the coldness feel even sharper.