So, thanks to the kind folks at r/arduino I know what I was doing wrong. I feel pretty stupid, but I (obviously) should have connected 120 VAC to the SSR. They provided me with a helpful diagram:
Only remaining problem (besides the fact that I'm very leery to hook up 120 VAC) I don't know which wire coming out of the motor is the hot wire and which is neutral because they're both black wires.