The half cock position was Browning's intended manual safety and was referred to as such in the 1910 patents, along with instruction for lowering the hammer to that position with one hand. The patents also described the redesign of the grip safety tang that allowed the safety to be depressed with the back of the hammer spur.
With the exception of the Model 1900 with its sliding rear sight...which disappeared on the 1902...using the half cock for a safety was the way that Browning designed all his exposed hammer guns. Examples are the Models 1892 and 1894 Winchester carbines, and the 1897 shotgun.
The manual safety was added on request of the US Cavarly as a means to quickly make the pistol safe for hasty reholstering in order to free up both hands in the event that the mounted trooper found himself trying to hang onto a frightened, unruly horse...with the assumption that the pistol would be redrawn when that was accomplished. Of course, the manual/thumb safety made the half cock redundant and unnecessary, but it remained as originally designed until the appearance of the flat quarter cock shelf of the Colt Series 80.
The thumb safety, as many believe, was not added with the intent of maintaining the pistol in Condition One. The 1911 CAN be carried cocked and locked, but it wasn't designed specifically TO be carried that way. It's simply another option.