Oh yeah absolutely I agree. I felt like when Oda showed Shanks with the "glow up", it was the start of a more ominous, less appealing direction for him and the story. It didn't feel like Shanks to me anymore, not the character I fell in love with it, just an aura farmer and another stoic badass stereotype. Obviously he still has his nicer side and some humility but I don't like how different and much more "serious" he is now but it fits for him being a Yonko now and all he has inherited and been burdened with legacy wise and all this lore dump nonsense and such. I hate the whole Figarland thing immensely but I'm not surprised at Oda doing it at all, along with the Shameless Shamrock reveal too.
Shanks was already the truly one odd out with the Yonkos and now as you said, he doesn't fit into all this mythological framework and we've got Toei suddenly giving him a giant haki bird attack in the anime, like WTF? So close to a "semi canon" Haki susanoo at this rate lmfao.
Yeah definitely, Shanks should have been the final obstacle to the OP and thats what I always expected, either he guards the 4th RP or and lodestar or even laugh tale and its entrance to it somehow. The final ultimate gatekeeper and former apprentice of the pirate king to test if Luffy is truly worthy of being PK and can burden the responsibility too etc.
OP was originally mean to revolve around the Yonkos mainly as the final villains, but now Oda has stretched the plot out so much, even Luffy can't compete with it. It's so overbloated, so oversaturated and a complete shadow of the greatness it once was sadly.
Shanks was better when he was simpler and he was such a great, amazing framing device for the story, much like Iruka was to Naruto and Rukia to Ichigo. But now the story has lost its way and identity imo, its lost its heart and charm and its something completely different, unrecognisable.
But thats my random rambling/ranting as always lol.
I got Gemini to look over my rant and it summarised and responded to it pretty well imo too: