Salam all
"Or have you thought that the companions of the cave and the inscription were, among Our signs, a wonder?" (18:9)
"We relate to you their story with the truth; surely they were youths who believed in their Lord and We increased them in guidance." (18:13)
"And they remained in their cave for three hundred years and exceeded by nine. Say: Allah is Best Aware how long they tarried. His is the Invisible of the heavens and the earth. How clear of sight is He and keen of hearing! They have no protecting friend beside Him, and He maketh none to share in His government." (18:25-26)
"And all we relate to you of the accounts of the messengers is to strengthen your heart therewith; and in this has come to you the truth and an admonition, and a reminder to the believers." (11:120)
"And when Our revelations are recited unto them they say: We have heard. If we wish we can speak the like of this. Lo! this is naught but fables of the men of old. They also said, ‘God, if this really is the truth from You, then rain stones on us from the heavens, or send us some other painful punishment.’ But Allah would not punish them while thou wast with them, nor will He punish them while they seek forgiveness." (8:31-33)
Saying that the story of Prophet Musa and his companian (peace be upon them) is just a tale to show Allah(swt)'s forgiveness and nothing more, can make you unaware of the brilliant guidance and admonitions that you can extract from it (and from any other story in the Quran).