The Major Scale is the probably single most important thing in Western Music.
The major scale was among the first things you were ever exposed to musically, whether you knew it or not.
Rock-a-Bye-Baby? Row Your Boat? Twinkle Twinkle Little Star? Itsy Bitsy Spider? The melody of these, and most other nursery rhymes, use nothing but the major scale.
If you only remember only one thing from you’re first grade music class, it’s probably ‘do re mi fa so la ti do’. Those are the sounds of the major scale.
It’s the basis for the majority of songs across almost every genre in Western music.