The closest thing to this I could find would be Chocolate Quest/Better Dungeons. Then use a mod that adds in dragons and also use More Player Models to make your character look like a dwarf or elf. Sadly I don’t know of any mods that add ability scores or monsters like Beholders or Kobolds. I recently made a thread about how a minecraft d&d mod could work. If I knew how to mod Minecraft I would have made it by now.
Yeah the D&D ruleset is just flexible and fun. As for stats there is a Dragon Ball Z mod called Dragon Block C and it actually has attributes (like Strength, Constitution, Wisdom etc) that govern different things but they behave more like Dark Souls where you level up your attributes over time instead of rolling your attributes. That mod gives me hope that its possible to implement D&D mechanics to make a fully fledged rpg mod for minecraft.