“They serve at a sanctuary that is a copy and shadow of what is in heaven. This is why Moses was warned when he was about to build the tabernacle: “See to it that you make everything according to the pattern shown you on the mountain.” ( Hebrews 8:5 )
Growing up, my brother liked to build model planes. He would spend hours constructing a model patterned after a real plane. In fact, after the glue dried and the decals were applied the model looked very much like the real thing.
Old Testament temple worship was just like this. It was based on a pattern of the real thing that took place in the heavenly tabernacle. Moses was shown the entire thing when he met with God on the mountain ( Exodus 25:40 ). Then God instructed Moses to recreate this tabernacle and its practices on earth with a warning to make it exactly as he was shone.
This speaks to how detailed God is. The tabernacle, set up according to what takes place in heaven, was to serve as an illustration helping the people understand. The earthly system was a copy and a shadow of the heavenly system. It wasn’t a means in itself; it was a model or replica of the true system. It looked like it, it functioned like it, but it was merely a pattern and foreshadowing of the real thing. This is why Moses was told to make it exactly according to what he saw, because it was simply a model.
The main point the writer is making in Hebrews 8 is that Jesus, our High Priest, entered into the heavenly tabernacle to perform His priestly duties ( Hebrews 8:2, Hebrews 9:11 ). The model portrayed by the earthly priests, in the earthly tabernacle, is based on the pattern of the true tabernacle in heaven. The Levitical priesthood was given so we could visualize everything Jesus did there. Everything we learn from the Levitical priest is a foreshadowing to Jesus and His priesthood. God gave us these examples to teach us so we would have complete understanding of this true priesthood.
Just as the planes my brother built as a child helped him visualize how the real planes looked, they were never a substitute for the real thing. In the same way, we can gain a lot of understanding by looking at the earthly system as long as we understand that it is merely a copy and a shadow of the true system in heaven where Jesus resides seated at the right hand of God the Father because His work is perfect and complete.