It's been a while since we've seen Samuel L. Jackson's Nick Fury in the Marvel Cinematic Universe, but if Jon Watts had stuck with his original plan, the character would have appeared in next week's Spider-Man: Homecoming. Watts didn’t want the character to simply show up in the movie; he wanted him to serve as Peter Parker's mentor, rather than having Tony Stark, aka Iron Man (Robert Downey, Jr.), fill the role.
Watts told io9 that in "mood reels" made before he became director of Spider-Man: Homecoming, his story featured Jackson's character as the mentor:
I don't know what the situation would be, but (Nick Fury) would be a person he'd want to get in trouble with.
However, after Captain America: Civil War had already set up an impressive character dynamic between Stark and Parker, there was no way Nick Fury could have been deemed a better fit as Parker’s mentor. At that point, Iron Man was clearly the obvious choice.
The report also revealed that the mentor-protÃ©gÃ© relationship between Tony Stark and Peter Parker was also at the core of the pitch Marvel Studios President Kevin Feige gave Sony Pictures' Amy Pascal to persuade her to introduce the character into the MCU. So it doesn't appear that there was any real chance that Fury would show up in place of Tony.
In the comics, Peter's genius-level intellect, which enables him to make things on his own, is a key character trait. However, Tony's involvement in Spider-Man: Homecoming has many worried that he's doing most of the work for Peter. Jon Watts explained:
That was definitely a concern. But I felt okay with it, because we don't show that he's not good at stuff"¦I'd love to see more of what Peter can do when it's all his technology. It would be cool to see him hack the Stark suit and do some other things with it. We see him messing with the protocols [in this movie], but what if he disassembles it and builds his own thing? That could be really cool.