I feel that the first season was pretty neutral, maybe kind of left-leaning aesthetically, but it also aired way back in 2013.
The newer episodes are dropping more fashy lines. The Unity episode where Rick frames some minority alien group for something, and then says "sheesh, don't blame me it's the police who are racist"
Or the "future crystals" where rick keeps getting routed through fascist alternate universes with nazi morties, only to end up with a wasp rick where the entire wasp Smith family eats the (Black) math teacher larvae. Not exactly subtle.
The whole premise of the show also became even more over of a power fantasy in seasons 3/4.
https://www.youtube.com/watch?v=gMILvY_FJj8
Watching Rick and Morty gave me the impression that the creators are pulling their hair out going 'how obviously bad do we have to make Rick before chuds and edgy teenagers stop thinking he's meant to be good?' He's pretty much the most powerful person in the world (pretty much like superman where depending on the movie/comic he gets however much power he needs to win in the end), and due to being an all-around asshole he's incredibly miserable and makes everyone around him miserable too.
He tries to commit suicide at least once, a lot of episodes are basically 'can we fix <psychopathic thing> Rick did?', and plenty of plot threads resolve themselves as 'Rick succeeds at his stated goal but is still unhappy because of who he is as a person, and his unwillingness to change/grow from his nihilistic masturbatory smart-means-good worldview'.
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You got me thinking about the episode where they cleanse the "toxic" side of themselves.
Rick's toxicity is his nihilism, ego, superiority complex, etc.
Morty's toxicity is the opposite: his lack of self esteem, anxiety, etc.
They both come out a lot healthier, but Rick veered a bit more towards the "caring" side, and Morty a bit more towards the "selfish" side.
Their toxic selves were trapped in the chamber, and only healthy Rick wanted to get them back--healthy Morty didn't. In other words Rick was a liberal, a person whose heart is in the right place but his tolerance of intolerance always prevents him from growing. Morty was a moderate basically, looking out for himself at all costs but without the emotional dysfunction and seething of the altright.