Actually the Luke of TLJ is the one who has finally internalized the lessons of TESB. Rey says herself that Luke is purposefully ignoring his success in ROTJ (which repudiated Yoda and Obi-wan), but he has a reason for doing so - saving Anakin did not destroy the Death Star in the short term, nor the Empire in the long term. On the contrary, Luke sees his victory there and elsewhere as having a direct line to his hubris in training Ben.
And anyway, Luke in ROTJ is very pointedly not able to avoid the emotions affiliated with the dark side. He brings his weapon with him when he goes to see Vader. He gives in to his fear, anger, and hatred. It is only when he is on the verge of killing his father does his rationality come in, and he realizes what he has done - it is an exact mirror of the flashback in TLJ. Of course the argument then is that “he should have known better.” Well fine if you feel that way. But in my mind, the dark side is a constant temptation, and the factors leading to that moment in Ben’s hut were such that Luke was, in his arrogance, unaware of what he was getting into (it was a far more subversive challenge than the explicit manipulation of the Emperor on the Death Star). This arrogance is of course a mirror to the arrogance of the Jedi in the PT not realizing the fear and the anger they were giving into, which caused their downfall. Luke, seeing the cycle of things he’s found himself perpetuating, decides to end the Jedi for good. I don’t see any regression at all, nor would I call any of his actions “stupid.”
In terms of regression for Han Solo - that’s the point of his story. Yes he’s gone back to do the only thing he was good at, but it’s a sham, and he knows he can only stay away for so long. Who he is underneath is a man who’s irrevocably changed from the smuggler we see in the OT. And as for Leia, did we ever see her become anything beyond a Rebel leader? You certainly can’t argue regression, maybe stasis in terms of status, but certainly I’d say her motherhood (and her explicit leadership of the Resistance) is a progression (for a character who never really had much of an arc anyway, unfortunately).