You're right, it's not enough to JUST vote. Voting is necessary, but it's not sufficient. The first thing that needs to be done is what is being done now. People need to protest to make the politicians realize that it is dangerous for them to ignore how much people are upset about this. This by itself moves the center. Colin Kaepernick used to be considered an extremist, now he is seen as a moderate.
The next step is to do some serious thinking about what is the best way to fix this problem. A new atmosphere created by the demonstrations makes everyone in the country willing to consider solutions that would've been unthinkable before the demonstrations. Some of those solutions are misleadingly described as "defund" or "abolish" the police, but when you read the fine print there are some real possibilities that could make things better. Dissolve a current police department, and replace it with a new program that recruit some new people and retains only those former police who are willing to reject the old culture of racism. Pass laws that cut the pensions of ALL members of police departments who tolerate racist police violence. Will these work? I don't know, and nobody will know until we have done some hard wonky research to discover what will be the long term effects of strategies like these.
Then, once you have discovered which programs are most likely to work, vote for those people who will implement those programs, and try to get other people to vote the same way. Then, your vote will make a difference. As I said earlier, these demonstrations have opened peoples minds to new possibilities, and some of those possibilities just might work. I remember a time when hotels, drinking fountains, schools, and restaurants were segregated, and I actually had to argue with people I knew who thought that was legitimate. No one with any political power would dare say that now, and no one who doesn't live in their Mom's basement even thinks that. In comparison to segregation, which was held in place by centuries of habit and tradition, police reform is relatively easy. (which still makes it very, very hard.) The Police all work for the government, and you can change the government--by voting. It will take years, perhaps decades, but it is far from impossible, especially when people's minds have been changed by demonstrations.
I'm not going to tell you to be patient. If I had less privilege that I have, I would probably be every bit as mad as you are. I admire the courage and honesty that inspires you to say "I can’t even pretend to have any sort of viable solution, and I genuinely wish I had something even remotely constructive to say.about the fact that once again, the American people have been left to fend for themselves. . . " But I also find some hope in the fact that you referred to the solutions as only NEXT to impossible.
I hope writing articles like this might help you get a clearer awareness of your anger, so that it can serve you as a motivating force, rather than paralyze you with despair. Hopefully it will also leave you with enough clarity to envision possibilities for action, no matter how bleak and challenging the odds.