Hi Ken, I found this question tricky, but I'll do my best. You're right; the rings do orbit Saturn's equator. The reason for this is due to Saturn's equatorial bulge. Like Earth, rotational spin causes Saturn to be an oblate spheroid with more mass at the equator than the poles. The gravitational attraction then causes a moons orbital plane to slowly become level with the equatorial plane. Then when that moon is torn apart to form a ring, the ring remains on the same plane. Furthermore, the ring also experiences that same pull to be level with the equator.

Additionally, when a planet forms from a protoplanetary disk, most of the time, they form with their rotational axis close to perpendicular to the plane of the disk. Therefore source material for a ring/moon is already roughly oriented close to the planets equatorial plane.

Although I am passionate about the subject, I'm not an expert (I hope to be in the future), but hopefully, that helped answer your question. Feel free to ask more if you have any.