Oh, no memories at all? I thought memories were like, alright, ever since Saito started doing martial arts and such from the first post, and the sisters were doing some super big brain stuff like livestock shenanigans.

I suppose the confusion comes from this: what exactly does our instinct as three day old goblins grant us? Obviously, hunting and killing is an instinct, but where does our knowledge of crafting tools to more effectively hunt, making traps to more effectively hunt, or understanding that some things are dangerous (such as brightly colored berries) come from, if not from our human memories and knowledge? That's why it feels like it's pretty easy to overstep the boundaries between our differing interpretations of how far 'instinct' goes, and where knowledge begins.

That being said, I'm fine with retconning the whole 'Hoi, back when he was a human, knew how to make fire via fire-drill techs', if goblin instinct doesn't cover knowledge of making fire and they aren't at the stage yet where human knowledge is something they possess.