I started playing bass when I was 13 years old and was in a band that only played original material, no covers, for at least the first two or three years. So none of y'all would recognize the names of the first bass lines I learned, hell I can barely remember the song titles!
I think the first cover bass line I learned was Grand Funk Railroad's "We're An American Band" ...and I had to learn it on the fly: My group (the ^^^above-mentioned original band) was playing a local school fair and the other band on the bill had a flakey bass player who kept wandering out of the auditorium. At one point their singer came running up to me and said "Do you know 'We're An American Band'? We have to go on now and our bass player is nowhere to be found!"
By the third verse I pretty much had it down. And halfway through the second tune (a blues shuffle iirc) the other bass player magically appeared, so I didn't get a chance to learn any more tunes on the fly that day.