Has it been confirmed whether or not Ryder is N7 ?
I'd say s/he is if I had to guess, cause 1) they're a BW protagonist, they'll be a OMA badass, it'd make more sense if they were established as a super elite than being a hypercompetent newb. And 2) it would also make sense if they sent one of their best on a mission this important, especially if you're supposed to be squad leader for the expedition.
Of course it's also possible that the N7 person is the intended mission leader but *something* happens that makes them unavailable (stasis malfunction, prologue death a la Nihlus, going rogue, etc) so Ryder is put in their place either because they were 2nd-in-command, because they're the one that comes up with a plan while others argue, because it's put to vote, because something badass you do in the prologue mission, etc
From what we saw the PC isn't wearing the N7 designated armor. They've told us the N7 person we see in the trailers isn't us though. So my guess is Our Ryder isn't exactly N7 (they could still be a lower N 1-6, but only N7's can openly wear that designation on their armor and other clothing.) but the sibling and or parent might be. We are officially, "untested." which admittedly could mean anything, we most likely do have a military background though as again we are likely going to still have to pick a class, and our mission objective is to find humanity a new home and if anyone is going to do something like that it's probably someone with some kind of military/scout/ranger background.