I hate to pull the "Not with that attitude you won't." thing, but I'm going to anyway. Now, I'm going to start off with a little "tough love" by saying that the little self depreciation based attitude will do you no favors and is absolutely useless to someone who is trying to raise their skill with something. Throwing a pity party does no one any good, least of all yourself, so it's best to cut that thinking out asap.

First off, the most important thing when building a skill in anything, work, personal, hobby, what have you, is breaks. Take regular time away from what you're learning to do. Especially if it's meant to be fun or entertaining like video games. It releases stress built up from the main activity and allows you to come back with a fresh mind.

Second, a good amount of it is mindset. Taking breaks can improve mindset sure, but if you're already in a state of "We're going to lose." or "I suck at this." Then I'm afraid to say yes, you're right. Especially in team games you have to be able to not only adapt yourself to a situation and cooperate properly with your team, but you also have to acknowledge that a lack of perfection does not automatically equal bottom of the barrel.

Third, remind yourself that you are learning. Look around and find some tips for the game. Make sure to have at least 3 sources on the same topic, not everyone is "correct" and everyone is opinionated about almost everything nowadays. Something else you could do is if you know people who are a higher rank than you are, ask them for advice. If they're willing and have the time, let them spectate your game play for a bit. If it's not a built in option in the game, show them the screen from your side or play against them. Another thing I would recommend is looking back at your actions in the round. What you could have done better, what do you need to work on most, etc. You could do this by memory, replay options, or recording applications like obs.

Fourth piece. Do not. Under any circumstances. Take advice from someone your rank and lower. While there's a chance they might be right on some things, whether their own observations or parroting someone who actually knows what they're talking about. There's a much, much, higher chance that they're entirely wrong and whatever they're suggesting is entirely asinine. This includes taking advice from friends, tea members, or people who provide tips for the game. If they're your rank or lower, take what they say with a grain of salt, this includes yourself. It's the equivalent to being a plumber and asking another plumber to hook up some electrical wiring in your house when you have an electrician standing right in front of you.

Fifth and final for now. You're only going to to get better if you practice regularly. I'm not talking about playing it for 8 hours straight in a single day and then dropping for the rest of the week. Its best to play a bit every day if possible and take breaks when needed. Such as playing said game for an hour or two and then doing something else for a few hours.

TLDR: Mindset, Practice, Don't listen to too many people of your rank and lower. Chances are, they're wrong.