I was keen on pop music aged about 10-11, and played in a sort-of 'group', but throughout my teens I was interested by firstly folk music, then classical - and only around twenty did I take much of an interest in pop.
A thing I liked to do was use my basic musical knowledge (derived mostly from classical) to understand a bit about pop.
Because pop is simple, it was possible for even a modestly knowledgeable person to realize what was going on - although one thing I soon realized was that pop was more complex, and more diverse, than I had assumed.
For example I realized that within pop there was pop-as such, which was based on tonic-dominant harmonies (e.g. the Beatles) and rhythm and blues/ rock and roll based on tonic-subdominant harmonies (e.g. the Rolling Stones).
One of the biggest groups - Status Quo - had broken into the scene as a I-V pop group (Pictures of matchstick men) and then become the classic rock and roll I-IV outfit.
I recognized that punk rock was something new in terms of its use of minor chords in fast and aggressive music; and that its other musical innovations were singing in an English (not fake American) accent, machine-gun drumming and distorted rhythm guitars.
I was surprised to find that the loudest and most wild 'heavy metal' group - Motorhead - was actually a punk band in terms of its harmonies - and their sound was built on an unique strummed-bass guitar sound from Lemmy.
I was interested by the two trios which dominated early 80s English pop: the Police and the Jam: and that the fact that the Police singer played bass meant that the group was built around the unique and virtuoso rhythm/ lead guitar talent of Andy Summers; while the Jam's singer played guitar, therefore was restricted to rhythm guitar and their bass player - Bruce Foxton - was in effect playing lead on the bass as well as underpinning the sound.
I had always liked reggae (since the late 1960s) but couldn't understand what made it different: however listening to the 'two-tone' revival of ska and rocksteady (e.g. the Specials), I un-picked that the basis was (if counted as four to a bar) a combination of four elements:
1. off-beat rhythm (on guitar or organ)
2. coming down hard on the third beat (usually snare drum)
3. bass guitar which syncopated (in a triplet rhythm)
4. a hi-hat or other percussion tapping eight beats (semi-quavers) to the bar as background
And I recognized that the novelty group Madness, were actually great musical innovators, and had created a new and uniquely English (indeed Cockney) combination of singing, dance, humour, sentiment and a 'fairground organ' sound built up from ska.
Signs of a misspent youth, no doubt...