God is good. The Christians like to sing that in their children’s songs. In the adult songs the wording can be more sophisticated, but the meaning is the same.
Jesus is God. the churches also teach that to their children and adults. It is part of standard Trinitarian theology, (sorry about the big words).
So Jesus, being God, who is good, must be good. Simples.
These are some of the good things Jesus did.
When there was a crowd of people waiting for him in a town, so he turned his back on them, and went elsewhere
Likened a foreign woman’s actions to those of a dog
Walked into the temple armed with a whip
Disrupted the legitimate work of market traders
Verbally attacked respectable religious leaders.
This does not sound very good, but that is because most people conflate good and nice. Unlike the Sunday School songs, there is nothing to say that God is nice.
God’s plan is not that we should have nice things. God’s plan stretches far wider than me or you. God’s plan, an all encompassing plan for the whole universe, may involve you and me occasionally in a mall way, and that part may not feel good at the time, not to us. But it is but a small part in God’s big plan, and God’s plan is good. Very,very good.
What Jesus did was not nice. There’s nothing nice about torture and death. Sacrifice and blood is not nice. Especially for Jesus. but god’s plan to reconcile people to himself and to each other. That is very good.