It has entrances and exits for cars. It is not fenced around the perimeter. The local wildlife comes and goes as it pleases, and there is no way that Disney is going to put an alligator-proof fence around nearly 50 square miles of property.
I get that you've realized that your image of WDW as a 100% safe area wasn't correct, and that's bound to be disturbing. But it will never be 100% safe. That's not a reasonable goal.
I look at comparative risk. I know that bad things can and have happened at WDW. Children have been hit by buses and killed. People have died on rides, been bitten by poisonous snakes and spiders, been raped, robbed, had cars and resort rooms broken into. All of those incidents are highly, extremely unusual, and there is probably more chance of any of them happening to me in my home town than at WDW. Because Disney goes to great lengths to keep guests safe. The bottom line: I feel safer at Disney than I do at a lot of vacation destinations. Am I 100% safe? No. I'm not 100% safe anywhere, unless I build a safe room in my condo and never leave it. I look at Disney's record of crime, accidents, etc, and I judge it to be safe enough for me.
And in the end, that's all you can do, too. You judge whether an area is safe enough for you. You seem to feel that WDW isn't safe enough, and that's entirely your decision to make.