The Ultimate Universe is now returning to prominence, and it's very much deserved. Although now known for its more questionable elements, it was once one of the best parts of Marvel's line. One of the most praised parts of this alternate universe is the Ultimate Spider-Man comic book, which eventually introduced fans to Miles Morales. Despite this acclaim, the webslinger wasn't the true heart of the Ultimate Universe.
Source：https://www.cbr.com/ultimate-x-men-star-marvel/
