Wano was really full of bad writting decisions by Oda, like not showing awakening for some of the high ups from the enemy like Queen, King, BM and especially Kaido, rushing the SH fights while spending too much paneltime with useless Wano Folk, a lot of plots that either lead to something useless, like the 1% man, or didnt lead to anything at all like the Shinigami one, characters like Yamato being created for no reason at all and doing nothing to the story, etc.
All this things make for me Wano a bad tô average arc, but all that said, Shanks, who has been hyped for years as most likely the strongest character in the story, the heir to Roger, the mentor to Luffy, oneshoting Kid isnt bad writting, to me make all sense, whats Kid place in the story. Yeah Kid, Law and Luffy, with some other supernovas having minor roles, were responsable by the fall of the old Generation, but just by seen Kid and Law vs BM it become pretty clear that they werent as strong as her and had to use some tricks to deafted her, very different from Luffy who clearly defeated Kaido.
After Wano Kid and Law plots were to give the Road Poneglyphs to Teach and Shanks and let the final part of the Battle for the Throne that started after Dressrosa take place between the three real contenders.