The 33-year-old world number one is this week ending her 14-year boycott of the BNP Paribas Open in California.
Her father accused fans of racial abuse after the then-19-year-old was booed and heckled in the 2001 final.
And speaking ahead of her return, the American top seed admitted: "I didn't think I would come back."
However, Williams, who last month confirmed she would play in the tournament in a Time magazine interview, said the time "felt right" to return.
The 19-time Grand Slam winner added: "There's not one thing that said I should come back, that I should come back in 2015. I didn't even know if I would be playing in this year.
"I just felt like it was the right time for me to come back here and try to be the best that I can be."
Williams beat Belgian Kim Clijsters in a final marred by the behaviour of some fans who heckled her and her family, apparently in response to sister Venus withdrawing injured from the semi-final between the siblings.
The watching Venus was also jeered by the crowd at the final.
"The whole point of me coming back was not to necessarily focus on what happened 14 years ago," Serena added.
Williams meets Romania's Monica Niculescu on Friday.
Serena Williams says she never believed she would return to Indian Wells after suffering crowd abuse at the tournament as a teenager.