Ridpath's short poem begins with a plain claim: the present is the only thing we truly own. Tomorrow, he admits, will "likely" arrive, but that hedge matters. Even the next day is a probability, not a promise.
From there the poem looks far ahead, to a day when time simply stops. The line about our "essence" having "the last laugh" is the oddest and most interesting moment. It could mean that something of who we are outlasts everything, or it could be darkly funny, as though the joke is on our plans and worries. The poem leaves that open.
The speaker sounds calm rather than frightened. He lists what will happen to the world's things in a flat, practical tone: repurposed, recycled, re-used. The final line, about artefacts and a nature "that wasn't built to last," lands quietly. The mood is reflective and a little wry, nudging the reader to value the present without drama.