The average American believes what they hear/see/read (or even worse by word of mouth) on their respective main news outlets, much like anywhere else in the world. Which is why I'm so vehemently opposed to the partisan lies spread via news.
It isn't even just the news outlets themselves, but you have the press secretary regularly outright lying to the public. So unless someone happens to read an article debunking this then that is what they will believe.
This eventually culminates in an extremely warped reality that is extremely difficult if not impossible to fix.
As for the J6 when I first saw it I cuckled, because I knew there was no way it would accomplish anything except for being used as fodder against them in future as well as obfuscating the problems the previous years regarding the riots and Covid that have barely been addressed. Never did I consider the event as a positive one mind you, but I immediately saw the extremism in the reporting. Especially since I followed some of those that attended the rally as well as knowing their reasons for going.
Calling it an insurrection was a mistake and this shaped the discourse. Calling it a "tourist event" is merely using another extreme to pull the narrative back towards the middle where it belongs. It is very much like the "mostly peaceful" coverage we had previously. Sure there was peaceful elements, but we critiqued the violence. People didn't go around saying this is all Democrat voters and that it was planned by Biden, despite people like Kamala and her bailing out of protesters. This IS what many were saying w.r.t. J6 though.
The fact that people are so against news footage and information coming out highlights how people want to cling to their own view of the event.
If the records aren't corrected to more accurately reflect what happened on that day then it will be forever be incorrectly cemented into the zeitgeist. The public can only pay attention to an event for so long before moving on to the next.