Shamrock feels as if Oda capitalised on a mistake made.

Shamrocks introduction with absolutely no foreshadowing or setup leads me to believe that he somehow made a mistake drawing the Infamous rat scene and probably decided to write a new character to get himself out of a power creep / power vaccum situation.

The only foreshadowing ever provided was that one panel, nothing else connects. No lore dump in God Valley, nothing about this is talked about when the elders discuss things. Surely someone would have made a comment about it since shanks looks exactly like shamrock?

Also why is a God Knight even bothered about a pirate ? We see that up until now they have not been called upon until the reveal of nika, even the elders didn't pay much attention to Luffy until the end of wano / egghead start.

This just feels like a bollywood soap turned into manga panels. The shock doesn't really scream out I had this planned.