Luffy's goal is to surpass Shanks. It's part of their promise. Luffy isn't chasing Roger. As a matter of fact, Luffy has never once stated anything about being like Roger. Whenever Luffy and Roger are tied together, it's always by people on the outside. Never by Luffy himself.
Yes, his goal is to surpass Shanks. His personal goal is not Roger, it's Shanks. Luffy has never wanted to be Roger. He just wants to be the freest man on the sea, and the King of the Pirates is the ultimate form of that.
Shanks not being the Pirate King has no relevance.
You're right, there is a difference between the two. The difference is that Shanks is the embodiment of Luffy's goal and Mihawk is the embodiment of Zoro's. That says enough right there. Never made any sense for Mihawk to be greater than Shanks given Shanks' importance and Luffy's own greatness over Zoro. Going "beyond Shanks level and achievements" doesn't mean anything in relation to Mihawk's prowess.
Yes, his goal is to surpass Shanks. His personal goal is not Roger, it's Shanks. Luffy has never wanted to be Roger. He just wants to be the freest man on the sea, and the King of the Pirates is the ultimate form of that.
Shanks not being the Pirate King has no relevance.
You're right, there is a difference between the two. The difference is that Shanks is the embodiment of Luffy's goal and Mihawk is the embodiment of Zoro's. That says enough right there. Never made any sense for Mihawk to be greater than Shanks given Shanks' importance and Luffy's own greatness over Zoro. Going "beyond Shanks level and achievements" doesn't mean anything in relation to Mihawk's prowess.
That makes a huge difference. If Shanks was the very last thing Luffy had to do to become pirate king I would agree with you. He is not pirate king and he's not pirate King level. Gol D Rogers is the person that Luffy needs to surpass overall to become pirate king. Shanks just one of many obstacles Luffy has left to pass.
Luffy's goal is to become pirate king. Gol D Rogers was the closest person to being pirate king so clearly he has to pass him to become pirate king. To say Rogers has no relevant is to ignore everything that the manga has been telling us.