There is two components to morality:
First is holding to honor and light and judgment as reality, and not made up, believing in goodness and evil, and the light of God's leader appointed by him.
The second component, is rationally seeing consequences of evil actions and benefits of good actions. The light intuitively is not enough for this, analysis is often needed, for further clarification.
When Quran talks about a course divided into twelve branches and courses from the people of Musa, it means, his successors are all one light. But they apply differently in their different contexts and situation. That is why the Gospels is very different then the Torah and Psalms. Their Nubuwa appears differently as well, the way God communicated to humanity differed Prophet after Prophet after Musa (a).
The reasoning is needed and what level people are at needs to be assessed.
The Quran "Truth" that the Successors (a) guided by, I would say has:
(1) Light of God component, his life connected through the Imam
(2) Analysis of actions harms on society making them evil and the degree of evil
(3) Analysis of actions benefits and how they set aright earth and justice
(4) Context and manifestation in Quran for all three.
(5) Context and manifestation in Sunnah for all three.
This sense knowledge of good and evil is not just one of these and not the other.
Some people believe in light of honor and sword of God but get confused regarding morals, because they haven't analyzed it properly.
Half of the reasoning of Quran and most emphasized moral (good and it's counter part, evil) is marriage and Muta. Muta is explained throughout and why and for what reasons one should do it, and that it best avoided if can be and patience is better then it. But it's alternative for those who fear God's curse.
Marriage is taught as an ideal and why. Why marriage is half of the religion per hadiths, you can see Quran throughout talks about it, directly or indirectly.
Unfortunately, the allegory of the cave misunderstands all this and put's it all on platonic thing. Light is needed, honor is needed, but it's mostly about being truthful and analyzing things sincerely.
The light of truthfulness when applied, makes you analyze things truthfully and sincerely in search of truth.
Truth becomes manifest and clear, when sincere.
This analogy makes it like people are trapped and can't think outside their perspectives. The truth is they aren't thinking and are following their caprice and passions, and argue with truth by falsehood, and refute proofs and reasoning with conjecture.
This has nothing to do with light or shadows, but everything to do with DIRECTION.
THEY ARE RUNNING AWAY FROM TRUTH AND GOD AND REBELLING ON EVERYTHING HE COMMANDS.