As far as we know (without making up stuff), the principle of animal sacrifice didn't begin until much later. Animal sacrifices can still be a type of Christ even if the first sacrifice was not based on that principle.
Probably many had no clear IDEA that that was the principle, just that God required it, even when Moses spelled out the meaning of the blood in the Law, so the principle didn't really get laid out until the New Testament. Abraham probably began to get a glimmer of its meaning when God supplied the ram instead of Isaac, but there is no reason to think many had much of an understanding of the meanings that were finally revealed, just that they were to be faithful and obedient to God's requirements. Abel's animal sacrifice should certainly be considered part of that principle of the Messianic foreshadowing, just as the meaning of the promise of the seed of the woman through Eve was fully revealed in the New Testament. There is no reason for it not to be (without making things up).
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