The finale made it clear that he was found by a Jedi (Yasmine Al Massri's character) who took him under his guidance and trained him. However, his Jedi trainer was hunted down but survived during Order 66 when thousands of Jedis across the galaxy were betrayed and murdered.

It seems a flashback scene for the season finale of Skeleton Crew was filmed after all, as actress Yasmine Al Massri has shared some behind-the-scenes photos of her mysterious Jedi

Yasmine Al Massri shot a scene as a female Jedi (presumably Jod's master) for the Skeleton Crew finale, and has shared behind-the-scenes photos.