New Casting
I don't know anything about Tom Holland. I know they were all saying he was a good Spiderman in 'Civil War' but I missed it and didn't see his part in that movie. I figured that since they liked him they were going to next make a whole movie starring him.
But these other unknown kids (other than Zendaya) makes it seem like they're just picking kids from Comic Con or something to put in the movie. And they're connecting them all to the Marvel movie universe.All these young unknowns don't fit being connected to a famous superhero movie and all the older veteran actors (like Robert Downey Jr and Michael Keaton).