"Wicca" in its modern form was popularised by Gerald Gardner after the publication of his book Witchcraft Today in 1954, but aspects of paganism and witchcraft have of course been in existence for centuries. Gardner was a protegee of Aleister Crowley, the famous 1930s Satanist. Gardner's work reawakened interest in paganism which until then had been virtually outlawed in Britain by the Witchcraft Act of the 1800s, which said that witchcraft wasn't real and anyone who practised it was a fraud. The Act was repealed in 1951, hence Gardner was then pretty much free to say he was a modern-day witch. He modernised witchcraft and paganism, but he didn't invent it.
The Druids were a secret society from ancient Briton times. No one today actually knows what they did, because the Romans were so scared of them they exterminated them all and destroyed all records of their ceremonies and rituals. All the information we have about them now is based only on legend, and we know how reliable that can be. There are no real modern "Druids", only groups that call themselves that.