Actually Mickey Mouse was created on May 15th 1928, not November 18th 1928 with Steamboat Willie.
Here's Mickey Mouse's first cartoon and debut which none of the studios wanted to distribute due to negative audience reaction after a public test screening.
https://www.youtube.com/watch?v=H6c_WgxTsMoThen a second cartoon was produced in August 1928 which also failed to impress the studios to get distribution.
https://www.youtube.com/watch?v=4jZTSfuOFVEIt was only after 2 failures that Steamboat Willie was made.