If you play with friends try to develop a good team comp and synergy. There are some very deadly combos out there.

playing heal is not excuse to be ranked low you can affect the game a shit ton as an Ana for example.
Don't worry about the numbers tho. Just play all the time to get better. Not to get rank !

Playing to get better over playing to win may not give immediate increase in rank, but over the long term you'll see a significant higher rank overall

this is what I mean and it is something many of the good ranked players keep telling everyone when they ask how to gain rank etc.
And it's so true and often not taken seriously!
When you play to get rank every loss is a negative experience and negative experiences affect you mentally so your A-game goes down and you perform even worse
and this is why "tilting" is a thing.
Playing only to get better makes the competitive laddering a positive experience and every loss can teach you a lot! And whenever you start to feel exhausted about "carrying so hard"
and toxicity of people then just watch a stream for a while or make food or someshit. Playing games is supposed to be fun after all this is something more and more people don't realize nowadays. It is something many talk about but how many actually take it in to action?

I tend to avoid ranked modes in games so I can play in a better environment.
And I can still work on getting better at the same time.