We don't yet know who made up the name but it's pretty clear that the name "Marvel" was inspired by "Mar-vell". After all, in the comics, the title "Captain Marvel" first belonged to the Kree man Mar-Vell.
In the MCU, who knows about Mar-Vell and her connection to Carol?
It doesn’t seem like a story that Peter would know about, since Peter wasn't there during the events of Captain Marvel, nor did he spend much time with her while she was on earth seeing as she arrived part of the way into the battle with Thanos, defeated him, stayed for a funeral, then left for space. And in the trailer Peter doesn't even know where she is.
Even the people who were alive during the events of Endgame didn't see much of Carol.
Nick Fury, Maria and Monica (?) Rambeau, some of the Kree, some of the Skrulls, and Carol Danvers herself know about Carol's history. And it was definitely Nick Fury's idea to pronounce "Marvel" as a single word, based off this dialogue from Captain Marvel, which seems like foreshadowing to me:
- Nick Fury: You're sure that's what Marvel would want?
- Carol Danvers: Mar-Vell.
- NF: That's what I said.
- CD: It's two words. Mar-Vell.
- NF: Marvel sounds a lot better. You know, like the Marvelettes? Not ringing any bells?
Of all these characters who definitely know about Carol's backstory, Nick Fury is also the only one we know is also in Far From Home.