It's not all about number of slams. The way he broke the Fedal duopoly to leap-frog them and take the #1 ranking spot after 7 years in their hands was amazing. Both Roger and Rafa are still beating everybody else (hence their #2 rankings) and are fighting for every title. So everything that Novak has won, he has had to fight two of the best players of all time to get. Nothing has been given to him. That alone would have been enough to make him a legend. The man to beat Fedal.
Add leading his country to a Davis Cup title, 5 Grand Slams, 5 masters in a year and 3 Grand Slams in a row and all these epic battles ...
Even if he were to stop playing right now he would be considered a legend. No question about it.
Totally agree with you. You only forgot to mention the streak.