This shows that Joseph and Mary were not well off financially, yet the Lord chose them to be the earthly parents of His only begotten Son.
The Lord doesn't choose the way man chooses. Man looks on the outward appearance but God looks on the heart (1 Samuel 16:7).
Mary and Joseph were chosen when they were without: fame, position, or money. God entrusted the most precious gift He had to a couple who would surely have been overlooked if men had been doing the searching.
God isn't looking for ability, but rather availability. One preacher said, "The world has never seen what God can do with one man who is totally yielded to Him." In response, D. L. Moody said, "By the grace of God, I'll be that man." This uneducated man went on to shake three continents for God.
God will choose us too, if we'll make ourselves available to Him (1 Corinthians 1:26-28).