I'm not sure why people are telling you these things, but that ain't what's happening.
> The media seldom even covering peaceful protests
George Floyd protests, including peaceful ones, dominated the news for the summer.
> hazing of civilian populations with helicopters and patrol cars, and several months of increased police brutality
There were problems, but I'm not being an 'optimist'. The great majority of protests were peaceful and uneventful. The only helicopter incident I remember was in DC.
> Nothing meaningful has changed as a result of all these protests
You should turn on the news, because it's good! Police reform laws have been passed and candidates have been elected nationwide; every Democratic candidate embraces them now, it's a necessity, and candidates who are far more progressive on these issues win; for example, look at the new mayor of Buffalo or at all the DAs elected and re-elected in major cities. Even Republicans in the Congress have voted for removing Confederate names from military bases, etc. Everyone remarked how the Thin Blue Line was finally broken, publicly and dramatically, in the Derek Chauvin trial.
Much more needs to be done, but it's just a reactionary fantasy to say nothing has changed.
> Video after video, image after image of police brutality and negligence. Police departments blatantly fabricating evidence. And of course, more killing of black men and women under the most dubious of circumstances.
Right, this is what people were protesting. It's not going to change overnight.
> None of our actions made any difference - and certainly where foreign policy, the military and war are concerned ...
You're just saying that, with no support. For the other claims of futility, where we do have clear evidence, they were clearly false. Maybe the same is true here.
I think the important question is: Why is it trendy on the Internet to claim democracy is so ineffective, when the reality is manifestly so much better? What do people gain from deceiving themselves? Who gains?