What is the purpose of tragic flaws in literature?? Please help. I really don't understand
They lead to the character's downfall and make the character relatable.
Archetypal heroes have a fatal flaw, meaning some flaw in their character, which somehow either contributes to or leads directly to their downfall. Look to Odysseus: his pride causes him to ignore various warnings and gets him into dangerous situations he could have avoided. In Cristopher Marlowe's play Dr. Faustus, Faustus' overambition and excessive need to learn causes him to make a deal with Lucifer. Victor Frankenstein has the same flaw and his creation ultimately kills him.
The second reason to give the hero a flaw, and this is somewhat less relevant to the plot and might have just come as a side effect, is that it makes the character more relatable and/or serves as a sort of cautionary tale.