2022 has already featured Jujutsu Kaisen 0, part 2 of Attack on Titan's final season, and a hinted return for Hunter X Hunter. It's been a huge year for Shonen Jump, and its protagonists have grown tremendously over the year.
Shonen Jump protagonists are known for one primary common denominator: their constantly evolving strength. When considering the strongest Shonen Jump protagonists, it's important to remind they exist only within the confines of their own universe and how strong they are in that world with those rules.
Gon Freecs
Gon Freecs is the fun-loving (and often morally questionable) protagonist of the newly returning Hunter X Hunter. The young Gon is the son of one of the five strongest humans on the planet: Ging Freecs.
While Gon is certainly powerful and a prodigy with skills far beyond his years, there are many superior Nen users in the series. Between Hisoka and Gon's own father, there are simply too many powerful humans out there stronger than Gon (outside of his one-time-use contract against Pitou.) Even beyond humans, anything on the dark continent is beyond what a human can accomplish.
Deku
My Hero Academia's protagonist Midoriya went from quirkless to the inheritor of the world's strongest quirk: All For One. Someday, he's destined to be the world's greatest hero.
While Midoriya is likely to become the strongest character in the series by its end, currently he simply sits as one of the strongest students at his school. Currently, he's outclassed by his rival Bakugo, many pro heroes, and of course the main antagonist of the series in Shiguraki Tomura. Still, Deku at least wins the award for most adorable anime protagonist.
Itadori Yuji
The protagonist of Jujutsu Kaisen's main series, Itadori Yuji, is the current vessel of the King of Curses: Sukuna. Itadori is also blessed with incredible physical abilities.
Nobody can match Itadori in pure physical strength, and he's already proved to be on the level of very powerful minor villains like Hanami. However, at this point in the series, he's no match for the incredibly overpowered sorcerers that exist in Japan. In particular, he'd be no match for 0's protagonist Yuta Okkotsu or his mentor Gojo Satoru.
Kamado Tanjiro
Demon Slayer's protagonist, Kamado Tanjiro, is the wielder of both water and sun breathing as well as the lone living person Muzan fears, mostly due to his possession of earrings resembling those worn by legendary demon slayer Yoriichi and his overall resemblance.
Right now in the anime Tanjiro sits with his friend, Zenitsu, and love interest,Kanao, at the level right underneath most Hashira. He will of course get stronger, but currently, he'd be the weakest Hashira and isn't strong enough to take on an Upper Moon demon by himself. Still, the Sun Breathing user a powerhouse in his world.
Monkey D. Luffy
The protagonist of one of the longest-running shows in anime history, One Piece, has grown tremendously over the course of the series. Luffy's declaration that he'd become King of the Pirates has become more realistic over the years.
While there are still characters much stronger than Luffy like Shanks and Kaido, it can't be denied that the stretchy protagonist has made his mark on the pirate world in the over 1,000 episodes in the series. There are plenty of powerful pirates in Luffy's own crew as well, and individual power aside, a great crew is necessary for any great pirate.
Son Goku
One of the most classic anime series of all time, Dragon Ball as a franchise is even older than many of its fans, and its protagonist Goku has grown up right along with it.
Goku isn't the brightest Shonen Jump protagonists, but he's certainly one of the most powerful. Capable of destroying planets and fighting villains on a ridiculous galactic scale, Goku would certainly defeat any Shonen Jump protagonist in a one-on-one fight. However, in his own universe, there are much greater threats than Goku, such as Whis who could effortlessly defeat Goku at his current level even in the manga.
Kurosaki Ichigo
Over the course of Bleach, the protagonist, Ichigo, slowly became one of the strongest characters in the entire series. The red-haired soul reaper has a few more tricks coming in the new Thousand-Year Blood War Arc as well.
Ichigo was able to reach the absolute peak of his world's power, becoming able to defeat Aizen with the Hogyoku's powers available to him. It took Urahara to seal the deal in the end, but that was more due to the Hogyoku's infinite regeneration rather than any gap in Ichigo and Aizen's power. As it stands, Ichigo is perhaps only beneath Captain-Commander Yamamoto in the anime in terms of power when he's in peak form.
Naruto Uzumaki
The story of Naruto follows the titular protagonist Naruto Uzumaki on his way from a lowly Genin to reaching his goal of becoming the Hokage by the end of the series.
Naruto is undoubtedly one of the two strongest living ninjas in his own world by the end of the series. He and rival Sasuke Uchiha stand at the apex of all ninjas, and Naruto is arguably the stronger of the two by the time Boruto comes around. While Naruto isn't the uncontested strongest character in his world, he's certainly up there with the best.
Eren Yeager
From being a child that lamented his own weakness, Eren Yaeger's strength has grown at a remarkable level. He now commands the power of the founding titan and seemingly infinite legions of colossal titans.
As the inheritor of three of the Nine Titans, Eren is by far the most powerful person in his universe. No one person could come close to defeating him by the end of Attack on Titan, and part 2 of the final season revealed a new form that makes Eren the largest titan in history. Overall, it takes 5 wielders of the Nine and multiple Ackerman's allying to even take on Eren.
Saitama
After 100 pushups, 100 situps, 1o0 squats, and a 10-kilometer run every day for 3 years, One Punch Man protagonist Saitama became the strongest person in the world and an incredible hero.
The most powerful character in any universe was born of a gimmick: a character so strong he could defeat anyone with a single punch. Saitama, despite being the protagonist, is admittedly a bit of a joke character that shows up and does the bare minimum to defeat the antagonist after his allies struggle endlessly. However, he's canonically the strongest character in his universe by a wide margin.