I have a couple of theories
The first regards the origin of Freddy's glove:
While in one of the orphanages, Freddy went on a field trip with the other orphans to the Nautral History Museum, and when they passed through the Roman exhibit, Freddy was fascinated by the images of Roman gladiators wearing clawed gauntlets, and this would serve as inspiration for his glove.
The second regards the years before Freddy came to Springwood:
The town of Springwood endured 9 Egypt-like plagues over a 22 year period:
For 5 years, the town would endure time with blood flowing through the river.
For 2 years, frogs would overtake the town.
For a year and a half, lice would appear all over Springwood.
Almost a month after all the lice were gone, all the animals escaped from the Springwood zoo and wreaked havoc.
For 2 years, all the pets in the twon would get sick.
The people of Springwood would then spend 3 agonizing years with boils on their skin.
For another year, the town would be pelted with thunderstorms, and hail would reign down, and fires would randomly start.
For 4 more years, locusts would invade Springwood and eat everything.
And finally, the town of Springwood would endure 4 years of total darkness.
Some time after the darkness had faded, Freddy would move to Springwood.