Is it normal that my rotor dings my caliper when dropped at a angle

could be the brake pad striking the rotor when the impact causes it to jump a bit as the spring tension isn’t enough to hold it in place when the wheel strikes the ground. The resonance of the ping seems to indicate that it is being very briefly hit and not resting against the striking object after impact. You could pull the pads and see if it still pings. If it is the pads I don’t think you have anything to worry about. You could spread the spring apart a bit and see if that helps.