The tutorial is usefull for HUD, UI's, inventorys ... whatever one can think of.
You have a HUD that does not need to appear on the screen, dissapear, change positions ... whatever one can think of.
It just sits there for the whole game (i suppose). So yeah, make it global in the first level will do.
And if it is a not to complicated game, the HUD will stay clean on top.
But, pay a sec attention, if the HUD is layer 1 in the first level, and in some next level you need a layer more, and you start spawning on layer 1, you'l be back to complain that the HUB is not on top of everything.
This is why that advize, to have the same amount of layers in all levels, is a very good advize.
And to have a layer called "whatever you call your HUD layer" on top AND with the same layer number.