He did just as the Lord had directed Moses to tell him to do. The covering would be a reminder to the Israelites. It would remind them that no one except a son of Aaron should come and burn incense to the Lord. If people other than priests did that, they would become like Korah and his followers.
Abel had faith. So he brought to God a better offering than Cain did. Because of his faith Abel was praised as a godly man. God said good things about his offerings. Because of his faith Abel still speaks. He speaks even though he is dead.
Every high priest is chosen from among the people. He is appointed to act for the people. He acts for them in whatever has to do with God. He offers gifts and sacrifices for their sins.
He isn’t like the other high priests. They need to offer sacrifices day after day. First they bring offerings for their own sins. Then they do it for the sins of the people. But Jesus gave one sacrifice for the sins of the people. He gave it once and for all time. He did it by offering himself.
That’s an example for the present time. It shows us that the gifts and sacrifices people offered were not enough. They were not able to remove the worshiper’s feelings of guilt.