Paul growing downwards year by year

HCG Moule said of Charles Simeon:

"'Before honor is humility,' and he had been 'growing downwards' year by year under the stern discipline of difficulty met in the right way, the way of close and adoring communion with God" (p. 64)

Today our pastor, leaning on Jim Packer, mentioned the following passages in which Paul demonstrates the same growth.

1 Corinthians 15:9, AD 51-55:

I am the least of the apostles, unworthy to be called an apostle, because I persecuted the church of God

Ephesians 3:8, AD 60-62:

I am the very least of all the saints

1 Timothy 1:15, AD 65:

The saying is trustworthy and deserving of full acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost

(dates from IVP Dictionary of the NT)