Your original question stated “before 1976”
I started playing in 1976 so I’m not sure whether this counts, but I’ll give my tuppence worth anyway. I’m also from the UK, so a non-US (and certainly non Lake Geneva) perspective might be useful?
I was 13 and attending a very old state school (founded 1549) which had a plethora of extra-curricular activities. My childhood had been pretty grim, so the school was a salvation and I tended to join everything going for that reason. This included the war game society, which never really “grabbed” me until a lad from the year above appeared with the white box set, and persuaded myself and a friend to play. I’d never heard of D&D before, though I had read both LotR and the Conan books, so was familiar with fantasy as a concept.
I loved the game and spent my paper-round money on some figures as well as managing to get the white box from a nascent Games Workshop, which at the time was a tiny shop in someone’s garden just off the Shepherds Bush road in London.
So I was “there” as the UK D&D scene “exploded” with Games Workshop and various other shops, as well as being able to start a still-extant D&D Society at school. White Dwarf magazine played a major role as did Judges Guild products.
Beyond a simple (and enduring) love for the game, I wasn’t really a typical D&D player in late 1970s terms, so I can’t really say much about that aspect of the gaming culture. For me, D&D was part of a holy triumvirate with punk rock (with which it was largely contemporaneous) and rugby, whereas most of my fellow players were more traditional in music taste, less into sport and more into the early days of computers ( the name Caverns and Wumpi sticks in my head from an early conversation with a fellow player?)
I wish I still had my White Box Set in much the same way as I wish I still had my Never Mind The Bollocks vinyl LP!