Many commentators over the years have asserted that the “murderhobo” was generally what old school D&D characters amounted to “back in the day.” That may have been true in the hobby broadly but I don’t think it was true at the very beginning of the hobby and for some of those early players/DM’s, that hasn’t changed.
I have had the honor and privilege of playing Dungeon’s and Dragons in its earliest forms with some of the people who were employees of TSR in the 70’s and early 80’s when Gary was still running the show. One of the things that strikes me about how those guys play is the assumption that the player characters are heroes. The basic definition of hero, in my mind, is a person who risks personal harm to protect others.
Clearly there was some gray areas in the behavior of those early PC’s at Gary’s table. The characters could be rogues with some avaricious motivations. Thievery, particularly when perpetrated in the style of Conan (stealing from evil temples and rich assholes) is was part of that style of play. Characters in Original D&D are more or less rewarded for avoiding fair fights when possible and running away is definitely a good idea when a random encounter in the wilderness turns up an ancient red dragon. Being “heroic” was a somewhat fuzzy concept but it is clear to me that the old timers assumed and encouraged players to be more or less heroic. If civilization and the “good” / “law” aligned people were in trouble, the PC’s would set aside their search for treasure in order to fight off the baddies. As far as I can tell, in the early group of players, if push came to shove their characters would sacrifice themselves for the greater good. They weren’t playing murder-hobos whose only motivations were gold and experience. Their “code” might not have been purely good (lawful stupid) but it was one of recognizing that there were moments when the greater good of civilization was worth fighting for.