I wasn't interested in riffs to start with - I picked up a guitar to accompany my own singing.
The first songs I learnt (in one long weekend when I was 14) were:
King of the Road
Greystone Chapel
Words
When it came to riffs, TV themes was where I started - Crossroads (old soap opera in the UK) and the Batman theme. The Shadows stuff came after that.
On the rock front, it probably was Smoke on the Water (in E!) and Chuck Berry riffs (we were introduced to them by Fast Eddie's playing in Motorhead and, to a lesser extent for my little group of guitarists at school, AC/DC).