Now, explain why that argument doesn't apply to King Arthur, or Robin Hood or War of the Worlds, but does apply to Mickey Mouse.
I'm pretty sure War of the Worlds is copyrighted. I could be wrong there, but I'd be surprised if it weren't.
I remember reading once that the limit of copyright laws was at one point 25 years, but that companies lobbied to have the U.S. congress extend it to 70 years with the ability to renew the copyright indefinitely.