Sometimes I wonder, how confident were our ancestors when they thought fire was an element, or when the Egyptians made mummies and hoped they would come back to

Sometimes I wonder, how confident were our ancestors when they thought fire was an element, or when the Egyptians made mummies and hoped they would come back to life. Did they have the same level of confidence as we do today? That the "fundamental values have all been measured to a high degree"? If that's the case, then we can be as wrong as they were.