What reasons could Virgil have for choosing to closely follow the structre of the Iliad and Odyssey and even reuse characters from the two Greek epics? Doesn't this point to his lack of originality?

“what i heard was abominable,” said utterson. “it can make no change. you do not understand my position,” returned the doctor, with a certain incoherency of manner. “i am painfully situated, utterson; my position is a very strange—a very strange one. it is one of those affairs that cannot be mended by talking.” –the strange case of dr. jekyll and mr. hyde, robert louis stevenson write two to three sentences explaining how this passage creates suspense.