From the introduction:
Dedicated to 40 years of Adventures and Gamers, both Past and Present.
This work is a fan-made production created under the Fan Content Policy. No association with Wizards of the Coast, LLC or TSR, Inc. is suggested or implied. All content remains the property of its respective owners.
...
"[The original] rules were written for people with a background of gaming experience. This revision was designed to be easily read and used by individuals who have never before played a role playing game.
"In the half-dozen years since the original rules were published, the TSR staff has answered thousands of rule’s questions. The answers helped find the problem areas in those rules, areas which could stand minor improvements or were difficult for novice gamers to understand. This revision was aided not only by the collected gaming experience of TSR personnel but by the gaming experience of the thousands of players and DMs who sent us letters in the mail."
User summary:
The "introduction", quoted above, is attributed to Tom Moldvay, 1980, and was copied from a commercially-published version of the game.