I'm guessing this issue has been discussed at length in the other political thread, so we probably don't need to beat this horse here too. I'll just add a few thoughts and then let it go.
The whole existence of Black Lives Matter is predicated on an alternative reality in which Black people must live in constant terror because racist police officers are pursuing every opportunity to hunt them down.
BLM is a human organization, so naturally it contains some bad actors: people who advocate violence as a "solution", or exaggerate threats and fearmonger in order to scare people into supporting them. That's the standard playbook for the right-wing extremist groups the president thinks are full of "fine" people, but I haven't seen anything convincing to show that describes most or even many BLM supporters.
The existence of BLM is predicated on the argument that institutional racism exists, we should call attention to it, and enact policies to address it. Similar to the way the MeToo movement is predicated on the argument that it's time to stop being silent and looking the other way when sexism and misogyny allows a culture of sexual harassment to flourish. You hardly have to believe in some nightmare scenario about police officers "hunting" black people to support BLM, just like you don't have to believe that all men are sexual predators to support MeToo. Both notions are absurd on their face.
When you indicate the fact that the overwhelming majority of contact between police and civilians is peaceful...
True--but this is the logical equivalent of arguing that the COVID-19 pandemic is no big deal because the illness only hospitalizes and kills a small percentage of those who catch it. Just because the worst outcome is rare doesn't mean we don't need to take it seriously. We still have a very limited understanding of who's most susceptible to COVID, who will recover without issue, and who will succumb to it. It's the unpredictability of not knowing how much risk you're at that's the most serious part.
Similarly, yes, most interactions with police officers are peaceful--but especially as a black person, you never know when you'll run into the wrong cop at the wrong time, and whether that cop feels any sense of accountability for his/her actions if things escalate. George Floyd didn't go looking for a fight, and didn't even resist, and got his windpipe crushed for no reason. Again, it's that feeling of unpredictable risk--and lack of accountability--that drives the cultural mistrust of police.
...that the vast majority of homicides are intra-racial...
People bring this up all the time as if it means something relevant, and it doesn't. We live in a segmented society, where most people live in a community where the resident majority are the same race and culture. Communities of color tend to be more population dense and have a higher poverty rate, both of which are known to drive up crime. Most crimes are crimes of opportunity, and are perpetrated on the people and things within one's community. Ergo, most crimes--including homicides--are intra-racial.
It's simple numbers. How does this in any way imply that police brutality and institutional racism are not issues? Again, this is the equivalent of arguing that because people are more likely to die in a car accident than from contracting COVID, the pandemic is therefore no big deal and doesn't need to be taken seriously. Completely devoid of any logic.
...that Black communities are opposed to defunding the police, etc...
Very few people are in favor of literally defunding police departments. That's just another right-wing scare tactic meme meant to make supporters sound more radical than they actually are. What people want is for communities to put more money into services that can actually help them heal and grow, like mental health or job training resources. Stop asking police officers to do jobs they're not trained or qualified to do. You won't need as many police officers if you direct some of that money towards reducing crime instead of throwing law enforcement at everything after the fact. Of course it's a tricky balance to find, but people are ready to have those discussions, if various bad actors would stop distorting and fearmongering.
...you are either racist or spreading racist propaganda or engaging in implicit bias.
Well, I don't know you and maybe you truly are not doing any of those things. But by design, these kinds of arguments are expressly meant to invalidate BLM and contend that it has no legitimate grievance. That position is squarely at odds with U.S. history and stacks upon stacks of socioeconomic data. So they are inherently dishonest arguments, and tend to be the darling talking points of people who either have a racist agenda, or simply feel threatened and uncomfortable by the fact that 'white privilege' is a real thing and are grasping at straws to try to deny it.
Is any of that you? I have no idea. But you can't really blame people for drawing that conclusion.