(Note that this answer was originally written for the Christianity.SE site.)
The primary meaning of the word translated as "good", the Greek word ἀγαθός (G18 - agathos - Strong's Greek Lexicon) is "of a good constitution or nature".
God's nature is the very definition of "good".
But Jesus, when he became human, shed his divine nature.
Instead, he gave up his divine privileges; he took the humble position of a slave and was born as a human being. …
— Philippians 2:7 (NLT)
Jesus was no longer intrinsically good; he was tempted to sin just like any other human being. He was able to resist this temptation though, through the aid of God's holy spirit, just as any converted Christian is capable of doing.
But as a human, Jesus was no more inherently good, of himself, than any other human being.
See also my answer to What is the biblical basis for Jesus having one nature only, a human nature? — Christianity Stack Exchange.
And here is my answer to a related question that was just posted on this site: What mind was in Jesus that the Philippians were advised to also have?