>>> it was offering or sacrifice?
if it was sacrifice then please quote the sin Abel committed.
My point is that a blood sacrifice pleased God - whether it was for forgiveness or not. And God told Noah this :
And surely your blood of your lives will I require; at the hand of every beast will I require it, and at the hand of man; at the hand of every man's brother will I require the life of man.
Whoso sheddeth man's blood, by man shall his blood be shed: for in the image of God made he man.
Genesis 9:5,6
The point was that blood was paid for blood. And while it may or may not be clear what God required for forgiveness - it was clear from the beginning that He saw blood as an important thing ("The life is in the blood" He also said to Noah).
You referred to Jeremiah 7. Here's more context :
Thus saith the Lord of hosts, the God of Israel; Put your burnt offerings unto your sacrifices, and eat flesh.
For I spake not unto your fathers, nor commanded them in the day that I brought them out of the land of Egypt, concerning burnt offerings or sacrifices:
But this thing commanded I them, saying, Obey my voice, and I will be your God, and ye shall be my people: and walk ye in all the ways that I have commanded you, that it may be well unto you.
But they hearkened not, nor inclined their ear, but walked in the counsels and in the imagination of their evil heart, and went backward, and not forward.
Jeremiah 7:21-24
Israel was hard-hearted and idolatrous in their ways. They went after other gods and violated God's law. But they thought they could appease God with sacrifices. It wasn't that God didn't institute sacrifices, but rather that He was looking for obedience and the fear of Him. So when sacrifices are a
substitute for that, they are an abomination to God. Read Isaiah 1. God mentions (among other things) the sacrifice of rams. That was the very thing God Himself provided for Abraham to sacrifice in place of Isaac when He directed Him to Mount Moriah in Gen 22. God had already (in Gen 15) told Abraham to sacrifice a ram. And if you read Exodus 29, you find that the blood of bulls and rams was required for a sin offering for the priests when they are consecrated to God. And in Leviticus 9, the ram and a calf are offered as a sin offering for the sins of the people. It nowhere (in that passage) distinguishes between intentional and unintentional sins. However, in Leviticus 5, there is discussion of a "trespass" offering which is made for sins committed through ignorance. But there are other times where even the trespass offering seems to be for a sin that is not done ignorantly Look, for example at Leviticus 6 where a man lies to his neighbor.There is a trespass offering required.
So it isn't just for sins of ignorance that God required sacrifices.