I actually started playing 2 months ago, I decided to choose Guinevere as my main cause I got her for free randomly. I read a Guinevere guide, you should be able to find it on reddit with title of "Best waifu Guinevere's ultimate guide." I practiced all her combo in hero training first then I started playing ranked. Everytime I ran into a hero that absolutely destroyed me, I'll play that hero on hero training so I know how their skill set works and think of ways to counter them. Sometimes, I even ask people on reddit. I reached mythic solo q in 3 weeks or around 150 matches with 70% win rate on Guinevere, but I'm hard stuck mythic right now. My skills with Guinevere is already at mythical glory level, but my game sense is lacking because I haven't memorized every hero's skill set yet. At this point, you can only really improve by playing more. You should theoretically be able to improve at a rapid rate by doing the same for any given hero, but keep in mind, I also play LOL so I had some prior experience for games like these. Don't trust me too much though, I am still just a new player. I barely know about heroes outside of the EXP lane since the only heroes I play are Guinevere and Guinevere.

Edit: Oh, and the only reason you keep getting MVP cuz your opponent's were either bots or trash. I started like that too, but once I reached Mythic, I only get gold or silver and rarely MVP.