Family stuff

Spider-Man: Into the Spider-Verse is largely about Miles finding himself and the Spider-Man he wants to be. And, as we learn in the film, every Spider-person needs to experience loss. For Miles, it’s the death of his Uncle Aaron, whom he looked up to, but is eventually revealed to be Kingpin’s henchman, the Prowler. The Prowler chases after Spider-Man and, when he realizes it’s Miles, hesitates to kill him. That’s when Kingpin kills Aaron.
Aaron’s brother—Miles’ dad—see this and thinks Spider-Man killed Aaron. This only adds to his distaste for the web-slinger, but in the end, Dad is able to witness Miles defeating Kingpin and destroying the collider, so he changes his opinion and becomes a Spider-Man fan. He does not yet know his son is Spider-Man. Only his Spider-friends, and his school roommate, know.