Saul was so stupid that he was outsmarted by some lost asses (1 Sm 9:4). Nevertheless, the Lord chose him to become king and sent Samuel to anoint him (1 Sm 10:1).
Levi (Matthew) was a tax-collector, one of the most sinful occupations in his society (Mk 2:14). Nevertheless, Jesus called Matthew to follow Him (Mk 2:14).
The Lord chooses the most unlikely people to be great in His kingdom. "God chose those whom the world considers absurd to shame the wise; He singled out the weak of this world to shame the strong. He chose the world's lowborn and despised, those who count for nothing, to reduce to nothing those who were something; so that mankind can do no boasting before God" (1 Cor 1:27-29).
The Lord has chosen you to be great because He has called you to be His child. You must live not a minimalistic, superficial, mediocre life, but rather an abundant, holy, and eternal life. You are so precious that you were purchased at the price of the incarnate God's blood (1 Cor 6:20). You are so important that you can't become more important. You can only become more aware of your greatness in Him.
As unworthy as you are, you are chosen to be great. Become what the Lord has chosen you to be.