how do i win and raise rank without having to rely on the other 4 people in my party?

i play every position but mid, i think i do pretty well, but without being super long winded how do i win without relying on the other players? in my mind this is a team game but im on a losing streak and when i ask questions like how do i rally my players without being toxic. or what items should i buy on a specific hero, people in this sub treat me like im an idiot and i should be out of my ranking already and that i can do it on my own.
my statistic on heros are close to Devine rank,( maybe 10-40gp/exp short sometimes higher in the other aspects) i know my items, i know how to move and farm with my team, stack camps buy the right items both as support and core. when and how to push lane, my last hit deny counter is on point often with me having 20+ denies during the laning phase without sacrificing my own farm, how frequently rosh pops. but im still sitting in guardian-crusader hell, how do i escape?

also im seeing all these cool costumes on the forum ive asked a few times but nobody will tell me. how do i make those?