While it's not explicitly black and white, it's certainly close. "Fantasmagorie" was drawn in black ink on white paper and filmed using stop-motion animation. The lack of color was simply a limitation of the technology at the time, not a stylistic choice.
It's important to note that other early animated films existed before "Fantasmagorie", but they were often simple experiments with limited animation. "Fantasmagorie" is considered a landmark because of its more complex storytelling and animation style, paving the way for future animated films.