The idea of shedding blood for atonement wasn't new at this point, but it was establishing the understanding among the Israelites that without blood, there is no atonement. It foreshadows the coming Messiah, whose perfect blood ends the need for sacrifices and atones once for all who will believe.
The altar was the first thing one would see upon entering the Tabernacle. It was elevated off the ground, a large structure built of acacia wood. This wood was known for its resistance to decay, a practical consideration, but also symbolically significant as it represents Christ's humanity. Christ also, though "cut off from the land of the living" (Isaiah 53:8), did not see decay (Psalm 16:10).
Acacia wood was also characterized by the sharp thorns that it bears, calling to mind the crown of thorns borne by our Savior.
We see tremendous coherence throughout God's Word. We see harmony In the Old and New Testaments, as the Old casts light forward to the New and the New looks to the Old for context. What is your favorite example of how Old and New fit together so beautifully?