Here is a list of all those who have scored 75 or more on their ODI debut:
It can be seen that Rahul is 11th on this list, and the only one to have scored a neat 100. Just below him is SP Patil of the UAE with 99 not out. While there have been three 99s on Test debut, none of them were unbeaten. In fact there are no unbeaten 90s on Test debut.
SP Fleming was out in the 90s both on Test and ODI debut. Andy Flower and Desmond Haynes are among others who made a fifty-plus on both Test and ODI debut.
Note the big gap between the highest score here (148) and the next (124).
There is at least one case (Shahid Afridi, 102 in 1996) who scored a century in his first ODI innings (in the then record of 37 balls), not having batted in the first. Similarly Yuvraj Singh scored 80 in his first innings in his second ODI in 2000.
Here we see the list of all Indian players with 40 or more on debut, which was headed by Uthappa and now by Rahul:
Patel and Wadekar scored their fifties in India’s first-ever ODI. Sidhu is the only one here to do this in a World Cup match (1987), while PK Amre is the only one to score fifty-plus on Test as well as ODI debut. Both of them came against South Africa soon after its comeback.