Jersh thinking Eric Cartman is a "relatable character" is the same energy that you see from retarded left-wingers that think the demons from Frieren are "misunderstood".
Anyone that has seen the anime Frieren will know that the demons from that show are emotionless sociopaths that only see human beings (and other mortals) as prey and they could care less about their prey being individuals. But you have midwit left-wingers that think the demons are "misunderstood" and think Frieren is "racist" even though the show makes it perfectly clear on why the demons are objectively evil and there is no trace of good in the demons to begin with.
You see the same thing with Jersh thinking Eric Cartman as the "Good Guy" when South Park makes it explicitly clear on why Eric Cartman is not a good person.
Jersh may like Eric Cartman because the character is racist and antisemitic but there are other objective reasons on why Cartman should be no one's role model. So let's list Cartman's horrible crimes that are canon in South Park:
Voyeurism and Revenge Porn:
One time Eric Cartman secretly watched Craig's mom undressing where he then processed to record her naked and then uploaded the revenge porn of Craig's mom to the Internet.
Kidnapping and False Imprisonment:
Eric Cartman kidnapped Butters and then locked him up in a bomb shelter by tricking Butters into thinking the world was going be struck by an asteroid so that Cartman can take his place to go to a fancy Mexican restaurant called Casa Bonita.
Rape:
Eric Cartman sucked Butters' penis when Butters was asleep so that he can take a photo of Butters in this compromising position to humiliate Butters later on.
Child Pornography:
Eric Cartman took sexually explicit photos of Butters in his sleep so that Cartman can use this to humiliate Butters in-front everyone in the classroom.
Enforced Suicide:
When Eric Cartman was in anger management, after his therapist called Cartman 'fat' in the attempt to get a rise of out the kid, Cartman impersonated his therapist on his phone by tricking the therapist's wife into thinking her husband was having an affair where she decided to commit suicide afterwards (the wife not realziing she was tricked to kill herself by a sociopathic kid) where the therapist looked at Cartman in horror and Cartman replies, "I'm not fat, I'm big boned!"
Indirect Homicide and Forced Cannibalism:
Eric Cartman orchestrated the murder of Scott Tenorman's parents where afterwards Cartman tricked Scott Tenorman to eat his parents remains and Scott Tenorman to his horror wouldn't realize what happened until Cartman explained everything.
There's too much to list here but you can clearly see why Eric Cartman is not a good person by any strech of the imagination.
Is this someone you want to relate to or let alone be your role model? If Eric Cartman was a real life person then he would've been sentenced to life in prison or sentenced to capital punishment for his crimes. This really says a lot about Jersh mentally when he admits that he uniorncally idolizes Eric Cartman and sees the infamous South Park character as a role model for him.
Normal people don't laugh with Eric Cartman, normal people laugh at Eric Cartman because normal people know Cartman is a horrible person and it's hilarious to see Cartman's schemes backfire on him time and time again.