I really appreciate your take and honestly, I get where you're coming from. Shane is one of the most complex characters in The Walking Dead, and there's definitely a case to be made for him being a sort of “mirror villain,” the kind of person any of us could become when pushed to the edge. But I’d argue that’s exactly why this list didn’t put him at the top.
“Hateable” is super subjective — it really comes down to what kind of behavior crosses a personal line for each viewer. For me, it’s guys like the Governor, Simon, or Joe, characters who were deliberately cruel and reckless, who didn't flinch at putting kids or the elderly in the crossfire if it served their purpose. The Governor literally kept zombie heads in fish tanks for fun and gunned down his own people. Simon gleefully massacred communities. Joe was a predator in disguise. That kind of cold-blooded ruthlessness feels way more hateable to me than someone like Shane, who, while flawed, was ultimately acting out of love for Lori, for Carl, and yes, maybe a twisted sense of duty. He was the guy who kept them alive before Rick ever returned. His downfall wasn’t villainy for the sake of it, it was heartbreak, jealousy, and disillusionment. In many ways, Shane was necessary. Without him, Rick wouldn’t have become the hardened, pragmatic leader we see from Season 3 onwards.
So while I totally respect the idea of Shane as a “villain we all could become,” I think that very relatability humanizes him and makes him less hateable compared to the straight-up monsters we met later in the show.