Is Tithing the only part of the law that was changed / does a cheerful giver hath anything to do with Tithing?

The meaning is one who gives willingly without bias or reward (we are supposed to acknowledge our charity only to HaShem) what is needed to sustain the health of a neighbour or stranger. A cheerful giver does not dwell on their charity after offering it up to the Lord. The head of the church is Yeshuah.