I highly doubt that considering you totally think that Luke's arc was discarded as if he became a messiah by renouncing the dark side once after actually succimbing to it...
Finn's story is actually a double arc: to go from running away and hiding and not caring to standing up and fighting for positive cause and going from deriving drive from hatred to deriving drive from loving something (i.e. fighting for something not just against something). At the end of episode 7 he doesn't care about anyone but Poe and Ray, his goal was to run from First Order which he hates and he only helps the Resistance basically because their goals align in the moment as he wanted to save Rey. After that he is in a coma. He never had friends outside of his stormtrooper brainwashing so Poe and Rey are his first genuine connections and only people he cares about. Seeing as First Order is about to wipe out the Resistance at the beginning of TLJ he doesn't care to help instead willing to just run off and find Rey whom he presumably has strong feelings for but he is too naive to understand. Finn is extremely naive because all his life was basically an indocrination. So after being busted by Rose at the escape pod and trying to help Poe and Rey he agrees to a hail Mary mission to save everyone because it would help his friends and he has not much other choice anyway.
During the mission he is accompanied by Rose (who is basically a low-level resistance member who embodies the traits of what the Resistance is). Finn finds out that Rose is highly ideological - she cares for the children, downtrodded, war profiteering, animal abuse. She shows Finn that the world is not what it seems on the surface (challenging his naivety) and that if you don't take a side, if you don't have a cause for fighting then it's not worth doing anything - meaning comes from cause. Moreover she tries to tell him that the cause is not just hatred and destruction - Finn was happy to trample the city after seeing how bad the people there were but Rose is not truly satisfied until animals are freed, a gesture of preservation. Shortly after they are joined by the alt-Codebreaker who tells Finn somewhat of a similar thing - that the world is complicated and more than what it looks like on the surface but the true freedom comes from not choosing sides and just profiteering - a completely different outlook. As Finn is literally a blank slate at the beginning, purposeless and without direction, he is presented with two conflicting ways of life that he can choose.
The codebreaker however betrays Finn and Rose because Finn is too naive to recognise that somebody who just doesn't fight for anything would go for people who will pay more. A lot of people die because of that, because Finn put his trust in an amoral man. Finn realises that not taking sides is not moral, he regains his sense of morality through these experiences which is more than his attachment to people. However in his newfound fervor he is still driven by hatred of First Order most of all, so when he is saved by Rose from pointless suicide because he doesn't want FO to win (pure antagonism) and reminded that the true cause is saving what they love (cause to fight for) is his arc complete and what Resistance is about. He realises that Rose would give her life as he would but while his death would be out of hatred and destruction hers is out of love and preservation and she's willing to give her life for that. That sacrifice and betrayal of codebreaker shows Finn the reason to fight for Resistance because they are morally in the right.
So, to cut it short, his arc is basically his induction into being a fully fledged Resistance fighter from just a rogue Stormtrooper on the run. He learned from his failure the value of morals and through his experience with Rose the value of building/preserving something vs destroying.