That was revealed after yesterday's final, as he sat in front of the trophy following his 7-6 (2), 3-6, 7-6 (5) win over Benoit Paire.
"I'm really proud because it was a tournament of revenge," said a smiling Humbert.
"[Last year], I lost against four of the five players I played this week — against [Casper] Ruud, [John] Isner, [Denis] Shapovalov and Benoit — so it means a lot to me."
For that reason, Auckland will always be special for the 21-year-old, whatever he achieves in the future (and his potential seems almost unlimited). This was his first ATP title, and what a way to do it; claiming vengeance after some bitter losses.
Humbert started the week as the world No 57, and toppled three of the top five seeds, as well as a former French Open semifinalist (Marco Cecchinato) and Ruud, who reached an ATP final last year.
"I don't know if I realise what I did [yesterday] but I am extremely happy," said Humbert. "It was tough, really tough, and emotional as well. It was a lot of work, a lot of improvement with my coach, in the pre-season and the months before."
As he had done all week, Humbert displayed impressive mental toughness yesterday. He was playing his first final, against a fellow Frenchman almost 10 years his senior, who had become a cult figure this week with his emotional displays.
But Humbert was ice cold in both tiebreakers, especially in the third set, after he had earlier missed a match point chance.
"It wasn't easy in my head," said Humbert. "I had match point on his serve. I know I can do it better on the passing shot but I was calm after this point and I [wanted] to play each point one-by-one.
"I said to myself 'stay focused, play like you know and be yourself, you can do it'. I really wanted this title and I knew I had to be calm, to be in control of myself and I did it.''
Paire rued some missed opportunities — he won eight more points across the match — but was satisfied with the fight he showed.
"At the end like this, you can lose, you can win," said Paire. "You [toss] a coin and see what happens. It's good for him, he's a good friend, he has been playing well. I tried everything to fight, to come back, I did it well, so that is why I am happy."
The match was an epic, one of the best finals in recent history.
Humbert found his best when it really mattered, particularly in both tiebreakers.
Paire had his customary meltdowns, twice, over the umpire's interpretation after video challenge.
But the 30-year-old fought back from 1-4 down in the third set, and could glimpse his fourth career title. However, Humbert was too good in the tiebreak.
Paire kept fighting, saving another match point with an ace, but Humbert was not to be denied.