Most tripod heads have ratings for how much weight they are able to support. If you place 10 pounds of camera/lens on a head designed for four pounds, it doesn't matter how well made it is, it will eventually fail. The same is true of the tripod 'legs' themselves. They all have a maximum weight rating.

From your question it is unclear if your camera fell off the tripod head or if the entire tripod fell over with your camera still attached. In either case, I would be reluctant to trust a D5100 and a 55-300 lens on the tripod you linked to. It just looks a little too flimsy for my taste. I own a different Ravelli tripod that I use often, but it is a much heavier duty model and I have a heavier duty head on top of it.

Even when you have a set of legs and a head that are rated to handle the weight of your camera and lens, you still need to be sure everything is in proper adjustment. Depending on the design, the locks on each leg section need to be tightened periodically if they are the lever type locks. The amount of tension on the head needs to be adjusted for the amount the camera and lens weigh as well as the angle at which you want them to be held. Various quick release systems need to be either tightened or locked in, again depending on the specific design. A single loose adjustment anywhere could be enough to cause a failure that could result in damage to your camera. Designs that provide a form of positive feedback, such as the Manfrotto RC2 or RC4 quick release systems that click into place, might be better for a novice. But even the Manfrotto design can be 'clicked' into place without the other side of the camera plate wedged securely under the edge of the receiving plate. I've caught my camera + 70-200 f/2.8 headed to the ground with my left hand on a couple of such occasions.

Regardless of what design you use, it is never a bad practice to "test" things a little after mounting a camera and lens on a tripod or other support. Grip the camera and gently try to rock it back and forth or pull it away. You will discover quickly when you have failed to secure everything correctly.