The student pilot reported that during his first solo flight, as the airplane approached to land, he flared too early, before reaching ground effect. Instead of performing a go-around, the student pilot then pitched the airplane nose down, which resulted in a hard landing on the nosewheel first. The airplane subsequently bounced and landed back on the main wheels before coming to a stop on the runway. After shutdown, the student and instructor noticed damage to the firewall and lower fuselage. Examination of the airplane by a Federal Aviation Administration did not reveal any preimpact mechanical malfunctions, nor did the student pilot report any.