Sniffles the mouse was once described as "Chuck Jones' first star", but he only appeared in about a dozen Merrie Melodies and one Looney Tune in the 1930s and 1940s. He did have a cameo appearance in 1994's "Space Jam", but the fans who remember him at all generally remember his backup feature in the comic book "Looney Tunes and Merrie Melodies" (later simply "Looney Tunes") that ran continuously from 1941 thru 1961, a run matched only by Bugs and Porky. The feature had him teamed up with a little girl named Mary Jane, and in fact after the first issue was re-titled "Sniffles and Mary Jane". (In the 1950s this was renamed "Mary Jane and Sniffles".)
So is the "Beauty" of "Beauty and the Beast" in fact Mary Jane? The evidence in its favor includes: 1) The little girl looks like Mary Jane as she was drawn in the very first comic books; 2) She enters Dreamland the same way in the short and the comics, by having magic sand sprinkled on her; 3) In her adventures, she shrinks to toy (or mouse) size; and 4) In her adventures, toys and dolls come to life. Furthermore, although she is not called (or credited as) "Mary Jane" in the short, she is not called any other name either, so the short does not rule out that she MIGHT be the Mary Jane of comic fame.
In fairness, the creator of Mary Jane for the comics, editor Chase Craig (who named the character after his wife) never claimed to have seen "Beauty and the Beast". (In fact, when he developed the series, only three "Sniffles" cartoons existed and he had only seen one of them!)
Officially, the similarity of "Beauty" to Mary Jane is considered a bit of a coincidence, nothing more. But fans will always wonder if perhaps, in the back of the creator's mind, the little girl with the late night snack became Sniffles' longstanding friend.
(For the record, both the little girl and her tin soldier friend from this short make a return appearance in "Those Beautiful Dames" later that same year.)