Why does the Qur'an seem complex, and is the disagreement among muftis' fatwas on the same issue considered a disagreement in understanding the Qur'an?

The Quran is the word and revelation of Allah, sent down in a clear Arabic tongue, and made easy to remember. There is no complexity in it. If scholars differed in understanding some of its texts, that is due to the varying levels of their comprehension, as Ali (may Allah be pleased with him) said: "I do not know it except as an understanding Allah grants a man regarding the Quran." It must be noted that the Prophetic Sunnah (definition) is a source of legislation and an authoritative proof, just as the Quran is, and it is not permissible to rely solely on the Quran without the Sunnah in deriving Islamic legal rulings.