Mark 10:18 - there is none good but one, that is, God

Mark 10:18 (KJV)  And Jesus said unto him, Why callest thou me good? there is none good but one, that is, God.

Jesus is performing a teaching here that God is the ultimate source of all good.

If trinitarians want to insist that Jesus is good therefore he must be God, then how do you explain these verses?

The good man brings out of his good treasure what is good. (Matthew 12:35).

Well done, good and faithful servant. (Matthew 25:21, 23).

And a man named Joseph, who was a member of the Council, a good and righteous man.... (Luke 23:50).

For [Barnabas] was a good man, and full of the Holy Spirit and of faith. (Acts 11:24).

Jesus did the works of his father. Therefore, ultimately, it is God's goodness being reflected by Jesus. That is why he teaches this man that only God is good.

He clearly denies that he is God in the verse.