Vaalingrade
Legend
You don't even need that.I mean, what's wrong with fantasy worlds just having a narrative of "Some people are given hidden blessings by the gods. These people can grow in stature, skill, and will from risk. danger and exposure to the evils of the world to grow into people who can challenge the gods themselves".
D&D provably has adamantine as an element and depending on what you believed either mithral as it own thing as an element, or aluminum in easily located and mined form. These would be trace elements that would find their way into the food chain, meaning nothing about D&D's biosphere and biomechanics would be remotely like Earth's because everything's cells at plant level and above is laced with supermetal.