Nadal has been described as a humble tennis player, but don't be fooled if you think he's not competitive. He's both competitive and cares deeply about his tennis career and legacy. He might not say it out loud, but you don't win 20+ Grand Slams by 'simply trying your best.'
You become that by going above and beyond to actually 'be the best' which is what Djokovic openly speaks about. He's not shy about his sacrifices to be as good as he is. Nadal generally doesn't talk about the GOAT Race, but he admitted in a recent interview with AS that he's aware that Djokovic has more titles than him, making him the best.
I believe that numbers are numbers and statistics are statistics, and in that sense, I think he has better numbers than mine and that is indisputable. I don't drop any rings nor do I have an ego big enough to try to disguise a reality that is not. This is the truth. The rest are tastes, inspiration, sensations that one or the other may transmit to you, that you may like one or the other more.
Djokovic has the numbers, and Nadal has the popularity. It's all a matter of preference but the wording is key. Nadal didn't call him the greatest player of all time, he simply acknowledged that Djokovic has the statistical edge over him.
I think that with respect to titles, Djokovic is the best in history and there is nothing to discuss in that.
For some, that will be enough, but it's a matter of preference. Stefanos Tsitsipas famously said that Federer is the greatest for him due to his impact on the sport. However you approach it, Nadal is right. From a statistical standpoint, Novak Djokovic has put together the most remarkable tennis career ever.