If gravity works by pulling everything to a single point (planets centre), then what’s keeping the rings on their specific axis? Shouldn’t it be an even layer of debris around the planet?
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An orbit is a stable path around a body under gravity: bodies like to move in a straight line, and so to follow a curved path, you need to apply a force to bend that path. In an orbit, the force required to follow a closed curve (a path that ends back where it starts) is balanced by gravity.
However, the *speed* at which this balance occurs will vary with distance. If a body is in a stable, circular orbit, and you give it a little extra velocity, well, gravity isn’t sufficient to keep it in the same circle at its new speed, so that circle will grow, and it will find a new equilibrium. You can view this, entirely equivalently, in terms of distance instead of speed. If an object is “too far” for its speed, that distance will decrease until it finds an equilibrium (or it falls into the planet or leaves orbit altogether, but we can ignore those cases for now).
Now, that’s all fine and good if you imagine an object as existing in a single point in space. But real objects have a volume. A rocky body is going to be moving at one speed, but it will exist simultaneously at different altitudes. In turn, there will a different amount of force acting at different parts of the body as it completes its motion. This variation in force is called a *tidal force*. Tidal forces are greater at lower altitudes, and are greater for larger bodies.
If these tidal forces are very large, they can exceed the internal strength of the object in orbit. It will continue to break apart into smaller and smaller chunks until the parts of the whole are all small enough to withstand their internal tidal forces.
This is what is often thought to have formed Saturn’s rings: a “rocky” body (mostly ice) was broken apart by tidal forces. There are also other theories, but this is currently the most common one. This is one possibly reason why they are all on the same plane, because they were all (or nearly all) at one part one thing. Saturn’s rings are on a plane along its equator (that is, they rotate in the same plane that the planet does). This is because the moon that formed the rings were formed from the same initial mass that formed the planet itself. Likewise, most planets in the solar system are in approximately the same plane for the same reason.
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