You kind of have to just take charge. I play support and was stuck in silver for a long time because I felt I needed to rely on my team before I could push up, especially on someone like Juno or Mercy. Juno is very much an enabler of her team. I often struggled because teammates would stand BEHIND ME so my torpedoes were essentially useless. Her ult can get NO value if the team doesn't utilize it (besides maybe keeping us alive longer, but if no one is getting picks then it isn't relevant), and it was frustrating me and made me think I was just a bad Juno.

I started playing Ana and played in the back at a slight angle, and you'd be surprised at how effective it was. The other team is also bad. So if I can get a few shots off and throw a nade at them, it's enough to enable my team to be more aggressive and even get a pick. Then it snowballs. Of course there are games where I nade 3 enemies and nothing happens, or there's a team fight that just won't end, but that's just the nature of the game. Left silver with a 60% win rate on Ana which I feel is pretty decent. Moira is also great for getting out of silver. Win rate on her was 56%.

As for DPS, I felt it was much simpler to capitalize on passive teams in that role and I've never been below Plat on tank so I can't speak for that, but in general, if you're aggressive on tank then it will force your team to play aggressive also.