Because it was set in the new Ultimate universe, created by the Maker, whose from the old Ultimate universe.
Who's, with an apostrophe. And this is ultimately still the choice of the management at Marvel, not a fictional character. And it's them choosing to use the title "Ultimate Spider-Man" despite this having nothing to do with the "Ultimate Spider-Man" series from 2000-2009 that I have a problem with. In-universe explanations obviously don't count as excuses.
I watched it. I believe its a six or seven out of ten. Its fun and it has good moments, however as a movie its just an hour and a half of good animation, jokes meant for children, others not so much, a few "eh i know those!" and that's pretty much it.
At the end of the movie, when Bowser helps his kid, I thought he might turn out to be good, and nothing happens. He goes back to being Bowser, so I don't understand the previous "i might turn good guys" hint when he feels bad for almost killing Mario and the others.
No offense but I feel like these race swap characters shouldn’t be put in the category of said character. Or maybe a different tag should be mandatory?