It was more an evolution for me, the first cassette tape I owned had a couple of Kiss songs on it, which I listened to over and over. From there I got into Maiden, Def Leppard, among others, then I heard Puppets, and it exploded from there.
Initially it was early thrash stuff, Slayer, Megadeth, Anthrax, Testament, etc, then I got into the more extreme grind and death bands like Carcass, Napalm Death, Cannibal Corpse, Morbid Angel and Deicide.
I still listen to all these bands today, more than 30 years after hearing Kiss for the first time, even though my mother insisted it was just a phase that I would grow out of. My tastes are much more varied these days though, spanning many genres, the only constant being those sweet guitar riffs.
It is so much easier to be exposed to new music these days, which is a great thing.
Practice and time……and practice. There is no quick solution.
Any particular reason why those 3 songs were chosen if the technical aspects are still a bit of a struggle? A7X have a pretty large collection of material to choose from, why not pick songs that you know you can nail now?