When Jesus called His Apostles he chose men of very mixed abilities. Time and again they failed to understand Him. Time and again they got it all wrong and let Him down. Why did He not choose better people for the job?
If you had to be perfect in the Christian life to become a priest, there would be very few priests in the world. Also, one reason a priest is able to help those who are sinners and those who are doubters, is because he himself may be a sinner, and may at times have doubts.
The example of the Apostles is an example of imperfect men, but of men who WANTED to get things right. They wanted to be stronger, more faithful and so on - and through the working of the Holy Spirit they were to become so.
So following their example we should not be put off if we think we’re not clever enough or not holy enough or not anything enough. Those are things we can work at.
Every priest has his failings, but he also has the particular gifts that God has given him to bring to the ministry.
God knows what gifts you have, even if you do not yet know. So open your heart to Him and open your ears to hear His call.