Many people on the forum guess that Armor Guy is a character that appeared long ago.
But have you guys carefully read what Armor Guy said?
He said "that pirate ship"
Their new ship, Thousand Sunny, after setting sail, only went to Thriller Bark right? Luffy's previous ship was Gold Melody.
Therefore, Armor Guy is not a character that appeared before.
He also said "waited for a long time";
So Armor Guy must not be a character from Thriller Bark.
In conclusion,
I boldly speculate,
The person who changed Armor Guy's life is Pirate King Roger!!
Because Franky is Tom's apprentice, it's not strange that the ship looks similar.
Or maybe there's another story behind the lion head on the Sunny. That's why Armor Guy got it wrong.
Also, the reason Armor Guy wears armor is because he is from the era of the Pirate King. Like how old Cap is. So Oda deliberately made him wear armor to confuse us.