Who created the opera?
Opera, or the beginnings of, is thought to have originated with the Greek Tragedies.
As time progressed and music began with lutes, original flutes, etc and songs by Dowland etc emerged, the use of story telling or getting accross the written word through song became more popular.
The use of music in church settings, often without accompaniment also began to take hold in the writing of Gesualdo and his contemporaries.
The first opera to be performed that we know about is considered to be L'orfeo by Monteverdi. Brilliant Opera, but the singing style was much different than today and an art that has all but been lost except by the early music devotees.
From that, the idea of "opera" took hold, hence the beginnings of opera. Basically.