What is the significance of the bull in this set of Korbanos?
Rashi: It came to atone for the sin
of the Golden Calf.
Even though they had not yet sinned (Ramban on Pasuk 14 [See Rav Chavel's footnotes and Ramban, Vayikra 9:3 DH "Veyitachen']).
Rashi does not comment on the rams and the various types of Matzah that made up the set of Korbanos? (See Rosh on the Chumash).