because they both loved and were very close to the 4th and like any normal human being some part of those feelings would extend to the son he left behind after his tragic and sudden death? because Jiraiya was made his goddamn godfather?
That's not the "world revolving around Naruto" this is 2 people and normal human empathetic actions. You act like I want them to personally raise the kid like if he was their own, no, the problem is they don't even acknowledge his existence.
Both JIraiya and Kakashi ha stuff to do on their own, Sarutobi was the one looking out for him, also remember this is as story where 6 Year olds are expected to be ready to assassinate if the missions requires to, even if it was someone that was your friend before.
The Manga made emphasis to show that the Ninja world they lived in had little room for feeling and was shown that they were only tools for the missions on their respective countries, While Konoha was shown as the more friendly and less violent village out of the 5 Major villages, they were still a bunch of killers that kept that cycle of war by teaching their kids to be killing machines. not to mention more than anything else Naruto was basically Konohas WMD, and just like the other villages, he was seen as a weapon by the village leaders.
This is a series were the leaders of the village sent out a 13 year old to kill of his entire race including his Mother and Father and his sibling.