I have the mechanics of a slightly skilled potato, and play about 5-15 hrs a week. I played ow on/off for years and was hardstuck for a long time. I decided I wanted to challenge myself and hit GM in all roles only solo queue and recently achieved that utilizing the below methods :

1. Watch your replays. Why did your team win a certain fight? Why did your team lose a fight? Why did you get picked? Did your teammate get picked and you could have helped? Was the enemy team feeding and you were completely oblivious to it so their mistake went unpunished? Could you have done more, etc..
2. Read the flow of a fight. The easiest way to get a feel of when to press W is when the enemy is backing up. Conversely, back up when the enemy team is pressing W. Look at the kill feed and get a feel of how many enemies are dead/how many teammates are dead and act accordingly. Look at the Hp of the enemy and teammates. Did you invest 2-3 ults and got no kills? then back up because it might be their "turn" to use ults as you are overextended.
3. Set up off angles. I find that off angling works best as a DPS, but can be done by anyone. Setting up angles from multiple areas of the map creates a lot of pressure. Peak and engage from the off angle as your main force starts the engage. Just be careful to give up that angle if you get pressured out. Not worth dying for.
4. Understand when to engage. The best timing for an engage is when the enemy is not paying attention to you. There is also a hard and soft engage. Hard engages are going for kills and putting yourself in the enemy territory, soft engages are kind of like a light poke that you intend to bait cooldowns and disengage. Hard engage when your team engages or if you can guarantee a kill and live. Soft engages can be done to bait cooldowns, divert attention, build ult charge, etc.
5. Don't tunnel vision. Sometimes you get their support one hp and you just want to finish them off so you overcommit for the kill and die; meanwhile your ana died to a 1 hp tracer. You're healing your 75% hp mauga who is not in danger at all; meanwhile your soldier is getting dove on by a reaper. There is stuff going on all the time. You will be surprised at how many opportunities there are if you don't tunnel vision.
6. LOS/Understanding when you or an enemy is feeding. In general, especially prefight, you don't want to be in the crosshairs of multiple enemies. If you turn a corner and you see 5 people looking at you and you are standing there shooting at them, you are feeding. Get back into that corner. Take an angle where you can isolate a target. If you are low hp, get back into cover. If an enemy is far from cover and/or if they are in the LOS of you and multiple of your teammates, they are feeding and you should prioritize shooting them.
7. PC Specs/Settings. Arguably the most important. Get at minimum a 144 hz monitor and a pc that can support 144+ consistent fps if you can. Check your windows monitor settings that your refresh rate is the highest it can be. Make sure your monitor is plugged into your GPU and not your motherboard. Make sure you are using the latest HDMI/Display port cables as older cables might not support higher refresh rates. Check ow2 video settings and ensure you are playing at your highest resolution/refresh rate. Make sure you turn on latency and FPS in your ow2 settings and ensure you don't get any random drops (if you do, something might be wrong with your internet or PC). If you read this and don't know what I am talking about, research everything I said and ensure you check all of these boxes.

I tried to make the advice pretty general across all roles, hopefully these tips can help someone rank up.

Is there any possibility that the Thunder Doomfist skin is ever coming back? I've only started playing OW since a few months ago and I really want the Thunder skin, but I've heard it was tied to Overwatch League which isn't around anymore. But considering there are currently OWL skins in the shop right now, does that means there is a possibility that Doomfist Thunder could return? especially after the Mythic was underwhelming, I really want a good skin I can run on my main.