Williams' 18th grand slam title was secured when she beat Caroline Wozniacki 6-3 6-3 in the US Open final on Sunday, seeing her eyeball compatriots Chris Evert and Martina Navratilova on the all-time honour roll of major winners.
Her sixth crown at Flushing Meadows leaves her tied for third for US Open titles, level with Evert.
"It means a lot to me. I just could never have imagined that I would be mentioned with Chris Evert or with Martina Navratilova, because I was just a kid with a dream and a racquet," Williams said.
"Living in Compton, this [had] never happened before. I just never could have imagined ... I could have gotten this far.
"And then it was eluding me for three tournaments, I guess. But still that's a lot for me. I was like really excited to get it."
Williams said her Wimbledon exit, at the hands of Alize Cornet, was a monumental letdown, but it caused her to change her training loads.
"After Wimbledon I was just so disappointed, because like I said, I worked so hard," the world number one said.
"Six hours literally just training, training, training, non-stop. After that, I thought, 'Well, maybe I shouldn't train so much because the results aren't coming. Maybe I should just, you know, try something new'.
"I just went away for a week and a half and I didn't practice as much. I practised, but I didn't practice as long. I made sure I hit every day.
"At that moment I also realised I just needed to relax a little more. I put a lot of pressure on myself. I don't have to put pressure on myself, because like I said, I don't have to win another title."
Williams' singles exit to Cornet at SW19 was compounded by a bizarre illness, which saw her retire dramatically from a doubles match where she was partnering sister Venus.
However, the 32-year-old dismissed fears her body was crumbling, claiming her fitness was as good as ever in the twilight of her career.
"Well, I think if anything I have proven that I can play a lot of matches," Williams said.
"I have played a lot of matches in the past five weeks. I think I have proven I have the discipline to just be able to go in and out and just perform in every match and every tournament that I play and just give 100 per cent.
"I was doing that so well, so well last year, and I wasn't able to do it as much. Even though I tried just as hard, I just wasn't able to do it as well this year.
"So it was good to get that feeling back."