I think one of the best starting adventure modules right now is Arnold K's Lair of the Lamb. And not just me, even the curmudgeonly Bryce Lynch rates it a "Best" and the calcified comrades at Bones of Contention also gave it high marks.
In my own review, I said this about it:
The Lair of the Lamb, I think, is a new classic in old-school gaming. It is based on a universal fear of being hunted in the dark by a monster, yet in the context of a highly interactable swords & sorcery setting which yields strong, strange rewards for players who take a risk! The module demonstrates, through play, how much players can do, and have fun, with 1d6 HP, a knife, a background, and a goal: escape. The dungeon revitalized.
Given Lamb is based on such a universal concept and that the module itself is rather bare-bones, I think has an inherent flexibility to be re-skinned beyond its eldritch swords & sorcery feel. This is a strength of the module, and I think what Lamb shares with oft-mentioned TSR classics like The Village of Hommlett (in particular the Ruined Moathouse) and The Keep on the Borderlands.
Each one can be adapted to whatever setting the DM feels is best for their players or setting. So here are some suggestions for ways to make the Lamb fit different types of settings that might be at your table.