Meal offering because it could only be eaten by the priests and only within the precincts of the Sanctuary. We are commanded forever not to eat blood or fat.
Blood is the seat of life.
As G-d has given it, so we give it back. Must be via animals, not people. With the latter, no oil or frankincense was mixed with the fine flour. Through this you showed that this animal was designated as the substitute for the person who brought it. With inflation, the person might only receive a fraction of the value of what was stolen if he was paid off in currency.