The speaker insists again and again on being human, almost as if someone has doubted it or as if they need to convince themselves. They list what they lack: claws, wishing bones, a song to lure anyone in. What's left is plain and exposed, a person who wears "handed down smiles" to prove they are ordinary and fine.
But the poem turns on a hidden feeling. The "joker in my heart" is something nobody sees, a discarded card that cuts with every heartbeat. The speaker can still smile and laugh at the joke, yet the pain sits underneath. The final lines suggest that a weakness, which the poem never names, has put a relationship at risk, and the speaker never expected to lose someone over it.
The mood is raw and self-critical. It moves from defiant shouting to quiet resignation, ending with the blunt admission that being human means being mortal and flawed, "weak pathetic thing."