The fact that Big E got over far beyond his level of push is a clear sign how special he is. New Day were not supposed to get this over - and it's not just with kids, they are generally beloved. Hell, even during their most pushed days, they would basically put over the Usos in all the big matches. But he managed to get over and remain over for all these years despite WWE never showing the sign that they were going to elevate him. Compare him to Dolph, whom the promotion at least pushed close to the main event for a few minutes. Ziggler didn't remain half as over for half as long as Big E has. If we keep comparing him to Cage, then I would argue that Cage has been less over than his push in AEW, a total reverse of Big E. He's received far more booking support than Big E has and yet he doesn't really feel like much of a big deal imo.
He did a lot of goofy stuff to keep getting TV time, but unlike a lot of undercard/midcard comedy acts, his matches and his occasional fired promos would give enough indication that this is a dangerous motherfucker who can snap and kill anyone on the roster so you better not fuck with him. Of course whether that is utilized well is a matter of booking and how they follow up on the reign, but he obviously has the potential and the charisma that has kept him good and credible enough to immediately feel at home in that slot. Look at how massive that final quarter did compared to the rest of the show, as opposed to the usual trend of the 3rd hour having a sharp dropoff. I think it's very hard to say that there are very many people on the roster who have the kind of goodwill and pent up desire to see in the main event, who could have pulled a similar number. All this on the basis of a tweet he sent a few hours before the show.