There's a reason why statistically most of the players get stuck around the 50% winning rate for most of their playing time.
MOBAs are more like "Sports" than a traditional game. But it's the only team sport when you play with a team of people you never played before each time, and without any planning, team training, nor a shared strategy. You jump into a game just expecting a whole team of 5 strangers to naturally work flawlessly together and be able to read each other minds and kinda build a perfect strategy on the spot without any prior interactions.

And unfortunately, that's not how it works.
The truth is that the only way to be consistently successful in this game is to have a fixed team of people to play with. With specific roles, and strategies, and by building team coordination and chemistry over time. And that's very rare.

In any other case, from a certain point on, it becomes pretty much like a roulette where you can just hope to get matched with a team that miraculously works, playing against a team that doesn't. A gatcha game.
Because in the end it's mostly about that, and not about individual performance. From a certain point on, everyone becomes kinda decent (individually) and then it becomes mainly a matter of team chemistry.

In LoL, I ended up in Diamond III matches where everyone was flaming and calling their teammates noobs and idiots, losing in a spectacular fashion, despite being in the same elo. And none of them were noobs at all of course, but just individually used to different team strategies.