We need to start emphasizing what we have in common, help people see that ultimately we're really not all that different from each other. The internet lets people hide behind this isolating veneer that makes it too easy to just shout at each other and behave in extreme ways that would never be socially acceptable in the real world. Interacting in real life significantly moderates people's behaviour and when social media and the internet facilitate segregation and amplification of extremes, spending more time in person might really do us a lot of good.
We need to put people in a context where politics is irrelevant and a shared interest has the opportunity to bond people who would otherwise not meet. It's the only way I see of countering Identity Politics that try to be all consuming.
It would also be helpful to encourage people to focus on more positive events. Outrage culture is a thing, only exacerbated by social media, where rage = clicks/views = money. We need to change the economics of this equation. We would really benefit from a culture that gave more attention to people doing good rather than just focusing on the villains in society.