As noted on the Radar page, the show is rather inconsistent in depicting the Chipmunks (especially the Chipettes) as children, when they're canonically eight years old. Most small mammals, chipmunks included, reach maturity after at most a year, which means that if they truly are eight years old rather than the chipmunk equivalent of eight-year-old humans, they are adults.
In real life, yes, they are adults. But this is humanoid chipmunks we are talking about so they are more of the human years type of aging instead of animal years. In the live action movies, it is presumed that it is easier or cheaper or both to animate small chipmunks instead of the human sized ones so they are still consider kids until they reach age 21.
The villain in the live-action films is named Ian Hawke. Hawks are a natural predator of small rodents, such as chipmunks.
An interesting note about the Chipmunks is that Simon is sometimes allowed to go off by himself while Alvin has to sneak off for the same lack of supervision and Theodore is only rarely allowed to do this. The short answer? Dave only really trusts Simon to be unsupervised because of the blue Munk's maturity; Alvin repeatedly proves he can't be trusted on his own and Theodore, while trustworthy, is somewhat immature and thus needs his brother's supervision if nothing else.
In one episode, Alvin accidentally spills Simon's hair growth formula and tries to replace it with something he improvises on the spot. Simon drinks the concoction and it turns out that Alvin accidentally mixed up a serum that can alter someone's personality. It should probably go without saying, but what if Alvin had mixed up something harmful? It also begs the question of who's more reckless: Alvin for mixing together a chemical without knowing what it will do, or Simon for drinking something without confirming if it was safe.
In "Cookie Chomper III", the driver who accidentally killed Cookie doesn't bring back the kitten's body to Dave's house, only his collar. The Doylist explanation for this is that it makes the tragic scene more family-friendly, but the Watsonian explanation? Cookie's body must have been too mangled to bring back.
Given that they're school-aged and live with a guardian, yet still have jobs and commitments, the Chipmunks are child laborers.