Which is also a G (when played in key of C). In fact, it’s the same G note as the letter G in the alphabet song, since it’s the same song and G is the 7th letter.
Thanks. There are a few minor details in the melody, but considering the harmony and rhythmic structure, it's really not coincidental why that note is there.
In order to follow common practice theory and with that limited rhythm, there are very few ways in which that note would be any different.