It's also on GoG https://gog-games.to/game/diablo and Internet Archive https://archive.org/details/Diablo_1996_Blizzard
To play the source port all you need to do is copy some files from the retail into the folder and it's good to go. It's also got quality of life changes like monster health bars, widescreen support, and a stash that transfers across characters. There's also multiplayer for classic and hellfire!
It's just slower and has a bit more of a roguelike feel to it. It's true that D2 basically did everything better but the changes are so drastic that it still leaves room for D1 if you prefer that kind of play.