Then how come the Flying Thunder God Jutsu always been referred to as Minato's technique. I'm not pulling this out of my ass either, the Mizukage referred to it as "the Fourth Hokage's Instant Teleportation Technique" in chapter 562, and like I said before if Tobirama invented the technique then why doesn't anyone refer to it as his technique, no one is saying that the Rasengan is Naruto's Jutsu, everyone has called it Minato's jutsu because he was the creator.
Death god seal was also believed to be created by Minato.
Explain to me how a technique called Hirashin used by 2 people known to use space time jutsu , have the exact same name, and both put in the same level by Minato have no relation at all ? You're basically saying it would be perfectly fine for chidori to be called rasengan but it doesn't make sense, names have a meaning. Do you have any other examples of 2 others techniques sharing the exact same name but still completely unrelated ? Because as far as I am concerned that's a first in this manga and in a lot of mangas.
As for your point about the mizu it doesn't mean a lot when a lot of statements have been contradicted by further developments in the manga, it's just a statement made by one character at one point, it's not necessarily god's words otherwise Sarutobi is the god of shinobi ( stated by Iruka), only an Uchiha can defeat an Uchiha, Kyuubi is a natural disaster.... there are a lot of statements like that in the manga but there are nothing more than hyperboles.
One last point nothing really says Tobirama created maybe he simply learned it, maybe his use was rudimentary and it was nothing more than a support move we know nothing about that. And where exactly is it stated Minato created the jutsu ? He is the one who used it and gave it such hype but nothing about him creating the jutsu from scratch, it doesn't take away Minato's achievement anyway or his genius status otherwise all characters simply copied ridukou sennin since he's the one who created ninjutsu.
To be honest it's getting tedious, if you can't aknowledge at least the possibility the 2 are related then it's useless to debate about it any longer belive what you want and we are derailing the thread anyway I am not sure people are enjoying this debate in a thread which purpose has nothing to do with what we are discussing.