They come from God through Christ. God has established him as minister of a new covenant of life that replaces the ineffective written covenant of the old law. Paul's apostolate is God's doing. Paul's defense of his own importance as an apostle and his grateful awareness of his success invite us to reflect about what importance and success mean for us. The two concepts are related, but they have different overtones.
Importance is a state of being, being of significant worth or influence.
There are lots of reasons why people are considered important. It can be because of their credentials, generally accepted testimonies to their talents and abilities, like having Ph.D. or M.D. after one's name. It can be because of the office they hold. The president of the United States is important. It can be because of the resources they have at their disposal.