Off the bat and in your defense, I don't think we're going to be able to say Mario 3D games are the "Best or most creative game ever made", since that's way too subjective and impossible to define, really. But they are damn good.
But OK, on to the disagreements.
First of all, I think it's clear you're not being particularly fair. Every stage in Mario 3D World seems to bring a new gameplay idea or mechanic to the table. That's what makes it so freaking good. Like I said, we'll never agree on "most creative" and I think it's a pointless exercise to try, but if you don't think that game oozes creativity out of its pores, then I have to ask just how much of the game did you even play? I was constantly surprised how one stage would have a super fun mechanic and then they just dropped it after that, letting it not wear out its welcome. The creativity comes from the idea that they were obviously pumping out ideas one after another, to make each stage feel unique, and they did a great job. I don't know, I think in that regard it was simply fantastic and unquestionably creative in keeping the player feeling that the experience they are having is fresh.
Secondly, you call it identical to older Mario games, but are you just talking about how there is a guy named Mario that does indeed jump onto bad guys heads? Is it because they share some of the same power-ups or characters? I don't get how you can look at, say, Mario 3 and Mario 3D World and somehow claim they're practically identical. Maybe I'm missing something that you're trying to point out, if so let me know, but otherwise I just don't see it. The way verticality in the 3D World series alone is used, isn't ringing any particular bells from old Mario games, and that's a gigantic part of that game.
Third, this whole "bold new idea" thing grinds my gears a bit. There's no inherent reason why a game needs a "bold new idea" in order to be considered "the best". I actually think instead of one single bold idea, the game is littered with dozens of smaller great ideas, that somehow I guess you missed out on. Not having one unified singular bold idea doesn't count as a strike against it at all. Why should it? And if it does, then the collection of all of the ideas within the game, of which there are tons, ought to balance that equation right back out again.
Fourth, and IMO most importantly, can we just judge games based on their own merits? What is the point of bringing up old Mario games as if somehow just because something was done 20+ years ago, that you can't ever possibly revisit those ideas again, to flesh them out more with newer technology and a deeper understanding of what drives good gameplay? I have a 6 year old and his first and only Mario games so far are New Mario U, Mario Kart 8, and Mario 3D World. When he gets older and starts forming more informative opinions, he's still not going to be able to compare it to older Mario games, since they'd be 30 or 40 years old by then and he wasn't there to play them in their proper context. So would his opinion not count, just because he can't make that comparison, and can only judge Mario games based on what he actually sees from the game itself? Of course not, and I'd say that's a far more pure way to judge a game.
Although, to be honest, as I sit here and think about it I still have no real idea why these games are getting compared to old Mario games in the first place when they are seemingly so disparate in everything but them most superficial details.