Just looking at definitions, for "Jesus" to bring salvation for all humanity, uniting all tribes under one spirit of truth and law, "Jesus" would have to mean the coming of Justice for all.
So whatever laws, both divine or natural, that are universally true for all humanity,.
"Jesus" would have to represent perfect fulfillment and unity between individuals and the collective spiritual level that God represents.
[As for Buddha, his teachings are about receiving wisdom and spiritual peace by letting go of false attachments to selfish material thoughts and desires, and continuing to meditate on spiritual development toward perfect "wisdom and compassion" instead of being held back by impermanent material things. The universal wisdom that Buddha received and represents is also passed on and is alive today. His basic teachings are true and universal to all people regardless of faith or no faith, because they are about human nature and spiritual growth process. The reason people require divine grace and authority that Jesus Christ brings is where we are "unable to forgive and receive one another" because we cling to divisions and conditions from our personal biases. Some tribal, personal, religious or other biases are so engrained, the only thing I know that can rise above all those human conditions is the unconditional love and grace given by God in Jesus that includes ALL and excludes none (whereas individuals or tribes are used to excluding others). Even if you do not call it or recognize it by the name Jesus, that spirit of universal love/truth/salvation is what Jesus means in order to be the "Messiah for all humanity." ]
