I'm curious. What would you count as evidence?
You want a CNN interview with him or something?
How about a DNA sample and an FBI dossier containing all his intercepted emails?
What exact kind of evidence from the first century could there be that you would not discount the same way.
We've got every shred of the "emails" of people who knew Jesus well preserved in 5600 manuscripts from all over the Mediterranean and they all say the same thing.

Inheritance matters because prophecy foretold that Jesus would be a descendant of King David. The people who knew Jesus certify that he was "of the house and lineage of David". You can trace that lineage back through Mary genetically or back through his "stepfather" Joseph legally.

The ten commandments are derived from the Greatest Commandment, as Jesus explained:

Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets (i.e. the Old Testament Scriptures).

Then the Levites went on to derive hundreds of other laws to fill in more details for people who couldn't figure out how to regulate their behavior from first principles.

Christians are expected to derive their behavior from those first principles - "That we love one another."

Few of us do, but that is what is expected of us.