Whether Wonka is an origin story really depends. If the narrative details how Wonka developed his skills, personality, and motivations from the start, then yes. But if it jumps in later in his life, then probably not.
No. Willy Wonka is a fictional character from the novel 'Charlie and the Chocolate Factory' which was first published in 1964. Although the story is set in an imaginative world full of magic and wonder, it has no basis in real events from 1896 or any other time in that regard.
Willy Wonka is about a mysterious and eccentric chocolatier who invites a group of children to his factory for a wild adventure filled with sweet surprises and challenges.