Etymological question that isn't specific to Latin for you guys: it seems like languages evolve over time to become more simple. Is this correct? If so, how do more complex languages arise?

@Adam That's not correct, exactly for the reason you give: Nothing complex could ever come to be, unless you postulate something like a divinely given original language.

Two mechanisms for evolution spring to mind: Random change and changing needs. The latter means that old distinctions become useless and new ones become necessary, and stuff like that.

For example, the Romance languages aren't simpler than Latin in all respects, but in some they are.