With its Neil Young whine, Isaac Brocklike penchant for profane profundities, and sweetly innocent aura-not to mention its warmly intricate folk tunes-this debut will have you wondering why you’ve never heard of Southern California singer-guitarist Avigdor Zahner-Isenberg. Then you find out: He and his band just finished high school. That knowledge in hand, the headspace that birthed songs about “Summer Cum” and “Five Little Sluts” is easier to understand, even if the source of the album’s indelible melodies and homespun poise remains a mystery.