Numbers 3:12 And I, behold, I have taken the Levites from among the children of Israel instead of all the firstborn that openeth the matrix among the children of Israel: therefore the Levites shall be mine;
God had saved the firstborn in Egypt. Because He had saved them they all belonged to Him. They would have had to give their lives in service to Him. Every family would have given up their firstborn but instead God in His wisdom and mercy chose to call out another group. He chose the Levites in place of their firstborn.
So the men of God represented their own children that should have been given to the service of the Lord. They should more than willingly take care of the Levites. They represented them before God.
Today we have all been purchased by His blood. We all belong to Him. We should all live our lives as though we do belong to Him!