I think the most important thing we need to know about Jod is that he's a liar. He has multiple aliases and we don't know which one is real. He makes up stories and thinks that the crew that mutinied against him still likes him. He's a con man through and through. Every decision he's ever made is all in service of himself. And ultimately, he had the complete opposite life as the kids, which is why he understandably hates them. Since all that's left is the finale, I don't think we need any specifics for his backstory when his character throughout the episodes already informs us on who he is. In a life as unstable as his, betrayal is always imminent and life is never valued, money is the only stable thing that he can always rely on.
I've been reading discourse on it, and I've seen the point made that kids' shows typically focus on showcasing messaging of morals that are easily understandable by kids. We're so used to stories like these having the bad guy shown to grow a heart and make the right decision in the end.
But if we look at the story as it's been presented to us, almost every single adult figure we've seen the kids be exposed to has told the kids not to trust Jod. And now we know they were all right.
The message there to kids is: if multiple people tell you someone is bad news, they're likely bad news!
Also, stranger danger.
I honestly think it's more realistic this way than the "bad guy gone good," even if the "bad guy gone good" is a more satisfying story.
Because in real life, there are probably more people like Jod than we realize.
It's a strong message as well for the kids, because this entire journey has been about them learning more concerning what the actual world/galaxy is like, rather than the idealized, sheltered, and utopian-esque version they've been exposed to up until now.
Just because someone fits a mold from a story we've read in our eyes does not immediately mean that person can correlate to that story.
When Jod told Wymm that this wasn't like one of his stories at the end of episode 5, he meant it in the sense of Wymm being heroic, being capable of saving his friends in that moment. But we can now see that this had another meaning. Wymm thought Jod was one of the hero Jedi in his stories because Jod has the Force, because Jod saved them a couple of times, but the truth is that he's the furthest thing from it.
It isn't one of his stories primarily because Jod is not a hero.
One more thing on this:
This show is teaching kids, I think, to be observant about their reality and circumstances.
Don't take things at face value; see things as they are, as they're happening, and use that knowledge to make later decisions.
A great lesson!