The 26-year-old admitted that reaching the top of both rankings was something he had never imagined when beginning his professional career.
"I never even thought of getting in the top 10 bowling rankings or all-rounder rankings when I began my career.
"Fast forward to now, where you're on top of those lists, it's surreal.
"I take it with open hands, but at the same time I remind myself where I come from and what I've had to put in."
His contribution to SA's 2-1 series victory over Australia illustrated exactly that, with Jansen making an impact throughout the three Tests.
After taking four wickets and scoring 61 runs in Durban, he produced one of his most influential performances in Gqeberha, scoring 85 off 100 balls and claiming six wickets in the Proteas' innings-and-31-run victory.
Though his contribution was less spectacular at Newlands, he still scored 52 in the first innings and claimed three wickets as the hosts secured the series with a 176-run victory.
He finished the contest with 198 runs and 13 wickets, earning the Player of the Series award to go with his newly acquired world rankings.
Jansen believes the format remains in a healthy position, particularly when matches are competitive deep into the fifth day, despite a lack of consistent red ball matches being played at international level.
"I think it's in a very, very good spot, especially when you have Test matches going to day five, second session; it makes the game more attractive, it's not a case of Test matches finishing in two, two-and-a-half days.
"It's nice to be a part of those games and those matches as well.
"It's not always the best for your body, but it's very rewarding if you're on the right side of it."
Getting there required the Proteas to respond when the tourists threatened to take control, something Jansen believes they have become increasingly capable of doing.
