"And if He was a man, then how did He managed not to be tainted by the original sin?"
He was Made by the word and power of God, resulting in him being the 2nd Adam, like the 1st before he got naughty. So, he is not technically out of the line of the 1st Adam -> "tainted by the original sin" Quite likely not even Mary's egg, otherwise that would effectively make him a 50% line of the 1st Adam. The 1st Adam was not made of an egg, Jesus is either a 2nd Adam or he is not, no room for a half like Adam lol.
You are probably aware of how easy it was for the 1st Adam to sin, but despite all the temptations put before Jesus, he never sinned.
If he was a pre-existing one, as most wrongfully claim, it would have been easier to not have sinned.
Jesus was not God, the Bible says God cannot die and the Bible does not say, God died on the cross, but his Son did.
