Here are some points to consider:
1. It doesn't necessarily take a genius to master sage mode. Jiraiya in his youth was the loser of the group just as Naruto was depicted to be. He was by no means hailed as a genius like Orochimaru, yet he gained sage mode. Ironically, Orochimaru who was hailed as a genius failed to master sage mode. In short, sage mode itself doesn't require prodigious talent. It just requires the proper training.
2. As for developing multiple rasengans, rasenshuriken (and the smaller variant wind style rasengan) were the only ones that actually took some real innovative thought to create (and anyone, genius or not, can come up with an innovative idea from time to time). All of the rasengan variants that he showcased in KCM during the war (such as planetary rasengan, absorption rasengan, mini rasenshuriken, etc...) were either just Naruto re-sizing his rasengans (which Jiraiya taught him how to do, and which is not that prodigious), or Naruto using multiple rasengans at once in conjunction with chakara arms (and Bee is the one who taught Naruto how to effectively use chakara arms, so it wasn't just some individual prodigious feat from Naruto). As for the mini-bijuudama, that just came as a result of Naruto mastering bijuu mode (which was a result of friendship, not prodigious talent). Now as for the other elemental rasengan variants that he got after obtaining RSM (such as lava or magnet), you must remember that RSM grants the user a comprehensive understanding of chakara. Therefore those weren't prodigious feats of Naruto, but more so gifts from Hagoromo and the bijuus.
3. Uzumaki blood doesn't have nearly as much of an effect on someone's power as Uchiha blood does. Sure Uzumaki blood gives one enhanced chakara reserves, durability and vitality, but none of those things alone actually add anything to the person's arsenal. You could have all the chakara and vitality in the world, but if you don't actually train and learn any techniques then you are screwed in a battle because simply having a large chakara reserve and vitality won't give you the offensive power necessary to defeat opponents. On the other hand, Uchiha blood automatically gives you the potential to awaken powerful dojutsu that actually do automatically add powerful offensive techniques to your arsenal. Now I'll admit that this doesn't really come into play until mangekyou, but once you hit mangekyou your power level has just sky rocketed even if you don't train that much. In other words, if Sarada decided to stop training and to start sitting on the couch and eating donuts 24/7, but then Chouchou died and Sarada awakened MS, then it wouldn't matter whether or not Sarada was fat and out of practice. Right then and there, Sarada would be able to stomp Boruto even if Boruto trained every day. Do you see what I mean here? You know that MS grants that kind of power.
Conclusion: I am not trying to discredit Sasuke's hard work because he did train hard as well. I am also not saying that Uzumaki genes are worthless or that Naruto is a complete moron. I am just saying that you are significantly under-valuing the amount of hard work that Naruto put in to reach his level of power. Naruto actually had to risk his life multiple times to achieve some of the techniques that he got (such as summoning jutsu, sage mode: he almost became a frog statue, KCM: he had to fight Kurama, etc...). That is more work than most other known shinobi have put in.