Okay, from those pages, it seems to me that the Horsepower number can be derived from the measured Torque. This makes sense to me.

What I never understood was how an engine could have "a lot of torque" as opposed to having "a lot of horsepower" and that the two numbers were somehow unrelated and derived separately.

Knowing that one number is derived from the other sounds much more logical. So the horsepower will change depending on the RPM. Makes sense.