To further back this the idea of Shanks knowing about Ace – despite never being confirmed that the Roger Pirates knew (or didn’t know) of Ace’s existence – I find it hard to believe that at least Rayleigh (Roger’s first mate) was not aware of a son despite Roger telling his sworn enemy/rival Garp about it. Yes I know he entrusted him to Garp for his safety but I still find it hard to believe Rayleigh didn’t know.
People tend to use the fact that Rayleigh, Shanks or any of the Roger Pirates never interfered with the Ace’s execution or even approached him during his piracy as proof that they didn’t know of his existence. But in all honesty I don’t see why they ever would as it’s clear that Ace established that he wants no part of Roger since he took his mother’s name and it could be a possibility that he ran into a Roger Pirate and expressed his dislike to them(this is all speculation at the moment).
Additionally, at the end of Marineford, Rayleigh expressed sadness after Whitebeard’s death but showed no reaction/mention to Ace’s death or lineage which further proves that he may have already known who Ace was and how much he despised his father so he simply didn’t care for him – after all he had already acknowledged Luffy as the inheritor of Roger’s Will both in Sabaody and post timeskip.
As well with Shanks, it’s safe to assume that he had known about Ace’s lineage prior to Marineford. He expresses his shock to how similar his actions were to Roger but not by the fact that he was Roger’s son so it can be speculated that he’s known for a while.
What do you think? I love the idea that Ace was expected/meant to be “the chosen one” but instead Shanks discovered a hidden gem living in a bar in some backwater village and thus unknowingly awakened a beast that is our boy, Luffy.
*Theory by jujujustat