It's unfortunate to see that some people have such an attachment to the Bible that they pretend it says things that sound nice in contemporary society when it often said the opposite.
Look elsewhere for mythology that has anything nice to say about transpeople. Christianity is a force of hostility toward people that aren't men born male.
1) You're misreading the thread. Headcanonning Jesus as trans is not about what the Bible says, it's about what it doesn't. A headcanon is not necessarily supported by the author, it just has to be not actively contradicted. Nobody thinks early Christians were in favour of trans people.
2) The Bible does not have anything at all to say about trans people, positive or negative (I'm welcome to being proven wrong here). Modern Christianity does, but that's not the same thing.
3) Galatians 3:28 "There is neither Jew nor Gentile, neither slave nor free, nor is there male and female
, for you are all one in Christ Jesus." Emphasis mine.