[Jessica Jade]

A human would, obviously, eventually figure out that the Ring made one invisible, but they would not necessarily know that they would be able to further their "big schemes" with it. (Aside from the obvious benefits of being able to obtain information.) They would probably go through a process similar to Gollum's and the one that was starting on Bilbo.

So, in short, the Ring might have been "safe" in the hands of a human for quite sometime.-Kuruharan

I disagree. Hobbits ARE like little people--little in stature and have little ambition. And the modest ambition is what makes ALL the difference. How many humans do you know want nothing more than to live in their own little neighborhood,never to leave, and are never curious about the outside world? How many humans do you know are completely content and fulfilled with their lives? The nature of humans differs from that of hobbits. Men are simply more audacious and have a lot more pride. Thus, the tendency to want to control or rule people, which is almost nonexistent in hobbits, is undoubtedly a part of humans, which would allow the Ring to consume them much more quickly.