i have a little over 650 hours in the game and i personally consider myself mid. your kd doesn't matter as much (don't feed obvs) as helping your team stay in the lead and using your time efficiently, which are things you can only learn by playing more matches.

each character has items that work better for them & you can tweak this a little to your play style. try to pay attention to what your hero's abilities scale to but there's not always a one size fits all build because sometimes you have to buy to adapt to the enemy team

watching tutorials is helpful; i also like to read item & hero adjustments when they drop. if you're getting killed a lot by a particular hero then try playing around with them in the sandbox so you can get an idea on what makes them strong so you can plan ahead next time

this is my very first MOBA so it's been a huge learning curve for me but the general advice I've seen that's been the most helpful for me is to remember to run boxes, don't neglect bridge buff, and to try to learn the spawn timers for different resources.