How in seven hells am I supposed to level 1-60

The title is maybe a little melodramatic but still. The first part of this game is awful. I have one dude at 120, one at 110, and the biggest obstacle preventing me from having more is the vanilla (technically cata I guess) leveling experience. With full heirlooms it feels like I’m just doing the same thing over and over and over and over and over until I level up and realize that I didn’t earn any new spells.