I think rolling in freestyle is as old as the style itself and is probably a natural part of the stroke but for years coaches tried to eliminate it under the impression that it was wasted motion. I will find documentation for that statement later and post it.
Spitz was not the first to roll but Counsilman was one of the first coaches, if not the first, to recognize that it was actually helpful.
In the very early days of the Australian crawl, as it was first known, it was thought that it was suitable only for sprinting, but after Gertrude Ederle swam the channel using the crawl it was obvious that that was not so. Apart from a few strange and eccentric swimmers, such as the lady who swam it butterfly ( I'll find her name later) I think everybody since then has swum the Channel with the crawl.