Nagato was 34 years old when he died, but Kakashi was 29. This would set them at most, only 5 years apart. How can this be when Nagato was 7 when Jiraiya started training him. Later, Jiraiya started training Minato (who was a kid at that time). Then, Minato was an adult when Kakashi became jonin at 9. So, Nagato should be older than Minato. He should also be at least a generation older than Kakashi.
Minato died at the age of 24. If he were to survive, he would have been 36 in Part 1, and 39 in Part 2.
In Part 2, Nagato's age is confirmed to be 35, in the databooks.
This means there's a 4 year age difference between Minato and Nagato, where Minato is elder.
Kakashi's age was about 29-31 in Part 2, confirming that he's younger than Nagato by 4-6 years.
First of all we need to remember that when Obito approached Yahiko and Nagato (there age was around 15). At that time Minato was a Jounin and leader of Kakashi and Rin. So there is no point that Minato was younger than Nagato
It's pretty easy to explain. It doesn't make sense that's the eplamation. In the manga it's very much Portraits as if jiraiya Trained Minato after nagato. This makes no sense but that's the way it's portrayed. Even more so because from the evidence that we have from manga and databooks, it's pretty clear that nagatos Training still happened in the SECOND shinobi war.
We can deduce that because the thirdly was when kakashi was 13/14 of course it might have rages on before that But for nagato to witness it as a young child it must have lastet over ten years. Which would else mean that sakumo hate would have fought in this war which he as far as we know didn't.
We also know that dan died in the second war and after das death tsunade leaves the Village. Not only is she still There when jiraiya First met the Ame Kids, But she is still There mire than three years after when they get the message that the Kids died. So at that point we're still in the second war. Nagato and Minato are too close in age for it to make sense. Even less so because we know he didnt go Straight from training one child to the other.
It would Maybe make sense if Minato came First But from the way it is portrayed it seemed like nagato was First. Even if I dont like the whole 'putting jiraiyas time line together' even less when looking at it from a political perspective. The only way it Made some sense were if jiraiya went Straight from one Student to the other. That Would mean he had a still rather young Team that he just left hanging for three years to train the orphans.
Even more so he left konoha in a time of War for three whole years without repercussions and is still considered the Best candidate for hokage by just about anybody.
Okay the only way for this to make sense for the timeline to make sense is for nagato to be order then the databooks say he is or for minato to be younger but that still doesn't make sense but just say that the data books for the ages to have either never occured to narutos author when he wrote those or for the two ages to have been written by different people, that is the only way for any of this to make sense, at best these ages where never supposed to be examined and I guess we can say at best that the author of naruto didn't know what he was getting into when he started writing the back stories and the ages of the character, that is the only option so I suggest that we just go by how a more logical stand point, becuase if we can say some of the time in the databooks wasn't that much and for jiriya to be still thought of as a good canidate lets say that the war was nearling its end when he tuaght nagato yahiko and konan, and he either aged poorly or had so much stress that it made him look older, so lets say that minatos age is wrong and that he is a year or two older and that the second great shinobi world war ended shortly after jiriaya going to teach them and that would still make sense becuase minato would then get to the age shortly after jiriya got back and that is when the thing was formed becuase minato shouldn't be older then fucking nagato unless he got held back like naruto from the ninja school but we know that isnt the case so we have to make him younger to fix it and then we get to the point of it happening, it would make some sense for it to be like this.