Fire Fesivals are one of the few surviving ancient traditions dating back to prehistory. Fire is a magical substance with fabulous properties of cleansing (clearing dead wood, stubble, bedding straw etc), protection (from animals), transformation (ore into metal), and cooking and provides one of the basic human needs of warmth and light. Not surprising that it was used in celebrations and as a focal point for societies. Fire Festivals are known in many cultures for this reason.
Other celebrations such as Bonfire Night are probably remnants of a more ancient event and amalgamations of several unrelated events such as the Samhain fire festival and Guy Fawkes.