While you can blame a lot of stuff on those people, but not everything. We actually get an estimation directly from Kakashi about how much chakra Naruto has, when he's not directly tapping into the Fox. Naruto has about 4 times as much Chakra as Kakashi. And Kakashi doesn't have ANYTHING special going for him. He has no special blood lines, he has no demon beasts, he wasn't even from a powerful clan. He was a prodigy, sure, but lots of people are. And this was Shippuden Naruto, Academy Naruto presumably has way less Chakra.
Edit: Actually, that bit of the manga is worded awkwardly. Either Naruto has 4 times as much as Kakashi on his own and 100+x as much with borrowed Kurama energy that Yamato will help make safe, or he naturally has Kurama energy in him (don't need to conciously borrow more) and Yamato is sealing away those bits allowing him to only use his own which results in 4x instead of 100+x he's currently rocking. The latter possible interpretation means that Kakashi should be able to make dozens of clones to train with, since Naruto made hundreds/thousands while Yamato was there doing his thing, so I believe it means that naturally Naruto only has 4x without deliberately borrowing energy.
Too much or too little, it's a canon example of him having a HARD AS HELL time learning jutsu. So we don't got much reason to think we'd be as slow as him.
The time he matched Sasuke on learning to climb trees was AFTER learning, and thoroughly abusing, Shadow Clones. He wasn't using them explicitly to train, but he used them in every battle, in mass. Months or Years (depending on how many he made for that battle) of fighting experience, gathered every fight. Odds are his Chakra Control and general skill went up over those many battles, the dividends of which we see during his far faster learning rate during the series.
I suppose one easy answer would be, Naruto couldn't learn it so fast in this AU. Things are different, and even if we didn't pick this spot of the timeline, Naruto wouldn't have learned it as fast as he did. That, or Naruto is different from Canon.