I mean, she did try other things as well and that characterization is a bit reductive. More correctly I think we can say that "she's not him" is the only thing the Sanders->Cheney spectrum could ever agree on and nothing else she did "stuck". Sanders wasn't happy about the pro-israel stuff and Cheney probably wasn't happy about the "tax the rich" stuff.
Choosing one clear ideology and sticking to it might sound great to the progressives on here (and to people like Hasan), but I don't have the hubris to think she or anyone within the Democratic party establishment actually had the charisma to pull that off either (maybe Michele Obama but she didn't wanna do it so that's the end of that plan). Especially considering Harris had like 4 months to pull a campaign together and did not have any previous popular good will to rely on.
4 months is very short and no matter how right you play your cards a lot of voters will not know anything about you other than "she's not Him". Sometimes you can do everything right and still lose (not that she did everything right but I think a postmortem will need to look back way further than that at Biden and Hillary and those who supported them).
The FBI apparently learned some lessons on how to deal with Russian interference since 2016 and made some arrests this time around. Way too little too late though, and in January Trump's cronies will take over and that'll be that. Other countries should take notes though and start being much harsher on Russian trolls and their puppets. Unfortunately Von Der Layen recently fired the guy who was prosecuting Musk over Twitter so I'm not too confident anyone in power learned their lesson. Which is mind-boggling because russian-backed far-right parties are a meaningful electoral threat to people like Von Der Layen.