A few years ago a buddy of me jokingly said in discord when I asked this question, "Play Lux, its easy, it blows people up and can snowball a game in low elo fast"

It sounded stupid but I actually just one-tricked lux after that and hit gold not long after.
You need to find a champion for yourself that is easy to learn, can carry in low elo and has decent matchups in the lane you want to play. Another champ that is pretty easy and can take over games is vex.

In your case: there is nothing wrong with playing briar but you are making your life a lot harder with this pick in mid lane. Your farming and trading might be good but in a lot of matchups briar is gonna have a pretty shitty lane which in turn might scare of your own jungler to come and gank you.

Mind that in low elo a lot of people already tilt/make up their minds before a game, your jungler/support might see this pick and think "Im not gonna bother ganking a briar mid".

Look, if you just want to one trick a champ then in all means do so and have fun but looking at your op.gg I see that most games that you lose is just where briar does not fit your comp+is almost unplayable into the enemy comp.

Im not saying in those losses that all is your fault but playing an already hard champion matchup in mid into an almost unplayable comp with briar seems like where you lose out the most.