'Bumblebee' wasn't a great movie, it was an OK movie. A competent movie. Which compared to the other movies in the franchise makes it look like a revelation of pure genius.
It's like suddenly a lightbulb went off over some studio exac's head and they said:"Wait, you mean to say the whole cast, including the autobots *don't* need to be a bunch of obnoxious, bickering arseholes? And young women *don't* need to be shot like they're in a shampoo advert? Oh and how about a plot that is simple, makes sense and isn't just an overly complicated excuse for people to runaround on location, with explosions in the background?"
...and 'Mack and Me' and 'Explorers' and 'Flight of the Navigator' and holy crap was "ordinary people befriend lost alien/magical creature" a popular subgenre in the 80's!
Mind you, I suppose you could also toss in the likes of 'Terminator 2', 'Free Willy', 'Old Yeller', and like, every Lassie movie and 'Littlest Hobo' episode ever.
Really speaking though, it probably owes the most to 'The Iron Giant', right down to the amnesia war veteran robot and the bullied "loner kid who's really the smartest person in the room" with the dead daddy issues.