Shanks is the son of a former Gorosei and was found by Roger. His father probably died during the God Valley accident. The accident happened 40 years ago and Shanks is 39. Teach is maybe the son of Rocks or carries his will. A Gorosei supports complete order and Rocks ideology is probably anarchistic where chaos reigns. They’re the polar opposites of each other, exactly like Shanks and Teach. They’re maybe meant to clash with each other. It’s in their blood. Dragon is not agains the idea of a WG but hates the CD. He’s fighting against corruption, so he’s the middle way. Freedom and order in once and I think that Luffy will represent this. Shanks has also such a view because he got influenced by Roger.