Unlike the earth realm, humans from the Savage Beast Realm and even others could directly absorb mana from their surroundings. They don't have to rely on consuming Spirit Plants or magic pills although those things would definitely make them progress faster
In this realm, there are more treasures that could increase one's absorption talent or remove the impurities on their bodies since an absorption talent of at least 90% is necessary to become a Junior Mage
A fairly clean and pure body is required to become a Junior Mage. As for the reason or how to reach that rank? Currently, Rezen doesn't know
While he was fed with many basic information by Ivy, the fairy's database is incomplete, or should we actually say 'damaged'
Ivy might possess some high-level knowledge but lack some of the most basic information
If we were to compare Ivy to a book, this book might have missing pages or torn pages that are in random