My Five Nights at Freddy's Mega-Theory
Around 1973 the first location, FredBear's Family Diner, is opened. It has just one mascot, FredBear, aka Golden Freddy. It is not an animatronic, but rather a guy in a costume. It is here where the Purple Man kills the child that goes on to possess the Marionette, as seen in the 'Give Cake' minigame in FNAF 2. The place closes after this.
Around 1977 a second location is opened, called FredBear's Family Diner. The Purple Man does nothing here. Instead, person after person is getting killed by the 'springlock' in the FredBear/Golden Freddy suit. Eventually, after trying to cover up numerous deaths of people playing FredBear/Goldie, they decide to sell the company. This is supported by the recorded messages of the first Phone Guy in FNAF 3. Obviously, since they're "prehistoric", it means that at one point they were not animatronics but rather people in suits. And - correct me if I'm wrong - I don't think Phone Guy actually says they are scaring people. The recorded messages from Nights 2-5 I think are from the second location.
The third location is opened between 1980-1983 and is called Freddy Fazbear's Pizza. They are now using animatronics and the four mascots are Freddy, Bonnie, Chica and Foxy. This is where the Purple Man returns, wears the Golden Freddy suit, kills the five children in the back room, and builds Spring Trap. He kills the children and uses parts from Freddy, Bonnie, Chica, and Foxy to build Spring Trap. This is seen in the main mini games in FNAF 3. (Some people say that he used Spring Trap to use the children, however this doesn't make sense because the children were dead before he started to build Spring Trap.) He then is killed by the Marionette into the Spring Trap suit and later possesses it in FNAF 3.
The fourth location opened in 1987 and is where FNAF 2 takes place. It features the Toy animatrpnics, Balloon Boy, etc. The reason the old animatronics are so torn up is because pieces have been used to make Spring Trap (Bonnie's face, Chica's hands, and pieces from Freddy, Foxy and Golden Freddy), who is in the back room, but not active. Then, you know how on the third night, Phone Guy is all nervous because 'someone took a suit from the back'? Well, someone else took the Golden Freddy suit and killed five more children, stuffing there bodies into the toy animatronics. This new killer is the original Purple Man's son, aka Phone Guy. And, on night 7, when you beat it, it says you're fired and your name is Fritz Smith. This is a different name than on the Night 5 and 6, Jeremy Fitzgerald. This is because Night 7 takes place the week before most of the game, and Fritz Smith is the Phone Guy. Smith is fired for 'tampering with animatronics'. He had been messing with the facial recognition system so they wouldn't call the cops. This also why the cops don't show up when they attack you during the rest of the game.
Then, in 1993, the fifth location opens where FNAF 1 takes place. It's barely open for about 5-10 years before it mysteriously burns to the ground. Spring Trap, the Marionette and the toy animatronics are there, in the back room.
Fazbear's Fright: The Horror Attraction is the sixth and final location and opened in 2023. Spring Trap is finally active because the Marionette doesn't have total power anymore, since he and the others burned in the previous fire (which is why they all look black and scorched). Then, the final location burns as well, but Spring Trap somehow survived, as seen when the image on the newspaper at the end of Night 6 is brightened. All of the children's souls have been freed - but Spring Trap and the Marionette still exist. And, possibly, Golden Freddy.