Beastlords get Light Healing at level 18, not level 20 as stated above. My BL just reached 18 and has the spell now.
For those commenting about the number of levels between Shaman healing spell upgrades, I'll go along with alamed's comments. Shaman are not clerics, they have spells that clerics don't have and fill a different role. If your main concern is maximum healing ability, you might be happier playing a cleric rather than a shaman.