I went back over the details today and realized why so many of you were unhappy with the protagonist's current strength.
Let me say this first: I'm not trying to say anyone is right or wrong. I just spotted the main source of the misunderstanding while checking things over, so I wanted to point it out...
It seems many of you believed Jiraiya didn't know Sage Mode at this point, or even during the Third Shinobi World War, and only learned it when he was much older (I'm not saying that interpretation is wrong).
But when I watched the anime episodes covering Jiraiya's past, I remembered the narrator saying, "Jiraiya spent his youth learning Senjutsu," so I'd always assumed he knew Senjutsu (note that I'm not saying my interpretation is necessarily right).
Earlier in this novel, when Orochimaru came up, I also said his knowledge of Sage Mode came from Jiraiya, and hinted that Jiraiya was the reason Orochimaru coveted Sage Mode. Nobody challenged that at the time, so I never noticed that my understanding of this differed from that of many readers...
In other words, many readers understood "Sage Mode" through Naruto's storyline: the moment he learned it, he unleashed that power and took on Pain...
But I'd always been thinking of Jiraiya (since Naruto was the protagonist, I subconsciously left his growth curve out of consideration). In other words, I thought that when Jiraiya first learned Sage Mode, he merely caught up with a genius like Orochimaru.
So I also believed Jiraiya already knew Sage Mode when he was young, and that his achievements while using it amounted to nothing more than earning the title of "Sannin." Naturally, I therefore assumed Sage Mode had different levels and room for progression...
That was probably the main point where our