Goldensky, on many the inconsistencies of the JWs ransom doctrine you can read this interesting essay written by Alan Feuerbacher, a former JW:
http://corior.blogspot.com/2006/02/gods-justice-sin-imperfection-and.html
As to animal sacrifices, they are very ancient rituals that turned up in almost all cultures and predate the Hebrews: in fact, you'll find them throughout early Ancient Near Eastern civilizations and they were already practiced in Canaan before the Jews "conquest", so much so that certain scholars think the liturgy and the sacrifice system set out in the Law is a "yahwization" (an adaptation to the cult of Jahweh) of a pre-existent Caananite ritual (see for instance René DUSSAUD, Les Origines cananeennes du sacrifice israélite, Paris, Presses Universitaires de France 1941).
As a matter of fact, almost all the types of sacrifices prescribed and described in the Law ( zebah , zebah hayyamîm, šelamîm, neder, minhah, kalîl , tenuwphah ) have been found in Canaanite texts (especially from Ugarit, XIV sec. b.C.E.): see, for instance, the discussion in Patrick D. MILLER, Prayer and Sacrifice in Ugarit and Israel, in idem,Israelite Religion and Biblical Theology. Collected Essays , Sheffield, Continuum International Publishing Group 2000, pp. 84-100.
Behemot