The multiversal silliness offered by Rick and Morty pales in comparison with the family dynamic of the main characters — one might remember how Beth and Jerry's marriage violently tore apart the best couples therapy center in existence. It's not that they don't want to grow as people, but that their inner turmoil holds them back from true empathy.
Still, there have been several instances in which the cast has risen to the occasion and proved that they understand the awfulness of their past behaviors (even four seasons isn't quite enough, though.) In light of this, here are a few ways in which the characters have improved, and a few in which they remain stagnant.
Changed: Rick Is Slightly More Empathetic
For the longest time, Rick has been one brick short of being an all-out genocidal maniac. No, wait, he was literally a genocidal maniac. At least now, after reuniting with Beth, Rick has become a less selfish person (at least in some ways). He may not always enjoy losing control, but he prefers seeing his daughter happy rather than get his way all the time.
It's not like Rick can't experience misery, but he considers any form of emotional vulnerability distasteful. Then again, he was ready to off himself after breaking up with Unity, so it's anybody's guess at this point.
Stayed The Same: Rick Doesn't Know How To Love
The problem isn't that Rick doesn't try, he just doesn't try hard enough. The fact that he adores his child and grandkids is obvious, even if he doesn't show it. But Summer, Morty, and Rick would (and do) argue that love is meaningless if you don't actually express it.
In "Pickle Rick", he struggles to get to the therapy session, but his presence is satisfactory enough for Beth that she instantly accepts his demand for no more therapy. This clearly shows that Rick's fatherhood depends entirely on the simple act of showing up, which is the bare minimum expected.
Changed: Morty Has Become Confident
Over time and with every adventure, Morty's cowardice has mellowed out (along with his constant bouts of anxiety). He staunchly refuses to follow Rick's unreasonable expectations on several occasions, for instance when he "raises" his half-Gazorpazorpian son or when he absolutely insists on having a Dragon as his grandfather had promised him.
Unfortunately, Morty still shows signs of having an inferiority complex, but this is largely because his family thinks of him as "basically an idiot," reinforcing the negative stereotype of himself.
Stayed The Same: Morty Rarely Calls Out His Grandpa
While there have been times when Morty has stood up for what he believes his right — and is regularly proven wrong by Rick — for the most part he just goes along with whatever his grandpa wants.
The problem here is that their relationship occurs along the lines of friendship, wherein one pal wields considerable authority over the other (a bully, so to speak.) This allows Rick to pass on his antisocial traits to his impressionable grandson, which is partly why Morty tends to abuse Summer in a similar manner, even though he loves her.
Changed: Summer Knows The Value Of Family
Summer is not a scientific genius, but there is no doubt that she is the smartest one in the family, next to Rick. Given Beth and Jerry's personalities and non-existent parenting style, it is a surprise that their daughter grows up into a well-adjusted teenager.
To date, Summer has displayed how much she wants her entire family to remain together, as in "The Wedding Squanchers", where she wisely explains how blood comes before anything else, saying that "you don't love someone in hopes of a reward."
Stayed The Same: Summer Just Wants To Have Fun
In the beginning, Summer was the perfect incarnation of a teen girl, often going to extreme extents to prove that she was "cool" enough to hang out with the school elites, or capture the attention of some random jock.
This has progressed slightly, but she is pretty much the same social-media-obsessed high schooler who rarely takes her eyes off her phone. In fact, even in the Season 4 premiere, "Edge of Tomorty: Rick Die Rickpeat", she half-considers killing her father with extra cholesterol just so she can take a funeral selfie.
Changed: Beth Is Finally In Control
Beth is as psychologically damaged as her dad; the only difference being that she is unable to successfully rationalize her behavior with "logical" explanations. It takes her considerable time to find a measure of control over her own life, which begins when she splits up with Jerry in order to make some time for her own personal growth — and also because her husband gives her an ultimatum.
However, Beth slowly becomes less accepting of Rick's borderline abusive attitude, like refusing to allow Morty to go on any more trips unless her dad requests her son's permission beforehand, and politely.
Stayed The Same: Beth Is Not Actually In Control (But That's Ok)
Just as Beth finally finds herself in charge of her life, it gets taken away from her. She comprehends that Rick's promises of becoming better are basically elaborate lies (though she is unaware that her father mistakenly thinks he's telling the truth.)
For some time, Beth was worried about being a clone, because this would mean that Rick's words are worthless, but also that she wouldn't be his daughter any more — literally the only thing that she wants to be. Luckily, in "Star Mort Rickturn of the Jerri", Beth and Space Beth develop a connection; they are both fine with their present situation, and intend to move on with their lives, with or without Rick.
Changed: Jerry Is Learning?
Is he though? One might argue that Jerry's attempts at caring for his family are horribly misguided, and tainted by his own ridiculously low opinions of himself. On the other hand, his shameless cowardice does have its exceptions — standing up against the Mr. Meeseeks army planning to kill him, quickly identifying the best way to defeat Beth's Mytholog, as well as accusing Rick of having a toxic effect on his wife and kids (which, in his defense, is 100% accurate.)
In their "original" world, that Rick destroys by making successively worse potions, Jerry has become a nomadic hunter, and is doing really well for himself.
Stayed The Same: Jerry Will Always Be Jerry
Yes, current Jerry is a vast improvement on the utter disaster he was at the start of the series. But not by that much, to be honest. The man remains a craven, self-serving, ignorant, pathetic excuse for a human being, and that's singing his praises.
Jerry's certainty about things he knows nothing about is only surpassed by his need to prove himself right, regardless of the situation. For example, the whole debacle about Pluto and its planetary status, or his need to prove his goodness to the entire galaxy by literally threatening alien doctors to amputate his manhood.