Only the SRBs use solid propellant (APCP). The first stage is kerolox and the upper stage is hydrolox. Although you are a bit off the mark, you did actually hi

Only the SRBs use solid propellant (APCP). The first stage is kerolox and the upper stage is hydrolox. Although you are a bit off the mark, you did actually hit on the likely reason for the faster liftoff, which is that the SRBs have a much higher thrust-to-weight ratio than the SpaceX Superheavy booster.