Prequels are just sequels that happen to take place in-universe at a time prior to the original.
There's no hard-and-fast rules but typically a prequel will subtly reference the original. While it's not a requirement to see the original to understand the prequel, it's often a bit more enjoyable as you'll be able to spot those references.
I think the best analogy I can think of is Pulp Fiction. Could pulp fiction be re-edited so the entire film takes place in chronological order? Of course. Would it be as enjoyable of an experience? Probably not.