All you can do is play more games and learn as you go.

Everything you said is true, a simple tipp I can give even if it's not the most creative one is, play only 1 Champion for your first 30-50 games, look up the abilities of Champions in free rotation because that's the ones you are facing most of the time. When you get frequently crushed by a specific Champion you can look him up too (for me it was Cassio back in the day, I didn't know what she can do and got crushed by her over and over again).

This way you learn the fundamentals way faster, as you don't have to focus on all this complicated stuff this game contains and all of your own abilities. You get used to the auto animation of your Champion, farming get's easier. You don't have to focus on all the items and get a better grasp for powerspikes. You get used to the limits of your own and enemy Champions.

It may seem boring for some because the choice in League is huge but find a Champion that's attractive for you and spam the shit out of him, it's the fastest way to improve your gameplay.