It was a 'sort of' debut because Steamboat Willie was in fact the third animation that Mickey appeared in, following Plane Crazy and The Gallopin' Gaucho. However, the earlier two cartoons didn't appeal enough to distributors for them to take them on. Thus, Steamboat Willie was the first Mickey Mouse film to receive distribution, and it's considered important for many reasons, including the fact that it's the first animation to feature synchronised sound.
The title takes the - ahem - mickey out of comedian Buster Keaton's film Steamboat Bill, Jr. The title of Keaton's flick refers to a song, 'Steamboat Bill', which happens to feature in Steamboat Willie along with 'Turkey in the Straw'. In fact, what with the synchronised sound, an argument could be made that Steamboat Willie is the very first music video; it is, after all, a story built around two feature tunes. Consider, though, how quickly animated features with synchronised sound developed: it's only 12 years until Disney's Fantasia, a timeless masterpiece that wedded music and imagery so well. It's worth nothing that another part of the plot involves love interest Minnie Mouse almost missing the boat.
In the 90-odd years from his not-quite debut, Mickey has come a long way, and he's all over the place. Clearly, I can't avoid him, no matter where I happen to be strolling after work - whether it's on the entrance to a house in suburban Glebe after recording the audio of a spoken word gig, or in the window of a clothes shop in the high street of that fashion capital, Parramatta, as you'll see.
Although, in this instance, Mickey's activities are a little questionable. What exactly is Mickey Mouse doing, with his back to us, on this top? Where's Minnie now?
It seems somewhat of a distance from Steamboat Willie to 'motor-boating Mickey'.