So, now I'm gonna be the Debbie Schlussel here and arrogantly answer your rhetorical question.
It seems like your main focus is the simplistic, "Can't we all just get along?" and the answer is no. There are too many differences of opinion and ways of thinking, sometimes convoluted ways of thinking that violate principles of logic, and often in brains with scientifically proven defects, such as clinical narcissism or psychopathy.
Humans are a tribal species. We tend to pick a group and conform to their rules. We start to project ourselves onto others in the group, when they might not even believe the same thing. If we stay in the group too long, it becomes an identity, and personal growth is capped or restricted, because everything we can possibly learn is squished between those boundaries. We start to judge other groups as substandard, and lose the ability to learn from their customs, or to even enjoy their art.
"I listen to all music except country"
"I like all Asian cultures except the Chinese"
"I would never date an overweight woman"
All very mild examples of self-limitation. Lots of people have much broader prejudices. If we want to be harmonious, we have to continue pushing outside of our comfort zone. Most people these days do anything they can to avoid discomfort, and so they are incapable of change.
"If you meet Buddha on the road, kill him." A famous Buddhist saying I learned about from Mutabaruka earlier. It means that if you cross Buddha on the path to enlightenment, you have nothing more to learn from him, so shed him from yourself and continue on your journey. The "road" never ends.
Similarly, you should probably find ways to filter people out of your life who are halting your growth, and also not be disappointed when someone filters you out, because you are in a different place spiritually. Learn what you can from them and move on. At least, that's what I do. I tend to forcefully confront people that I disagree with, but only to the point we stop gaining anything from it. Then it's time to walk away, or sometimes lay them flat.
So the answer to your question, "How many rivers do we have to cross?" Too many to count.