Some of the earliest written interpretations of the Bible (the Jewish midrash) saw Adam, the first human, as being intersex and having both male and female characteristics until God made Eve later (thus separating male from female):

https://en.wikipedia.org/wiki/Androgynos

This is mentioned in the Jewish midrash, the idea of the androgynos is brought up in Genesis Rabbah, a Jewish commentary on the Bible written sometime between 300 CE and 500 CE. The commentator asserts that Adam, in the story of Creation, was created by God as an androgynos. It continues to say that later, when Eve was fashioned from his rib, God separated out the sexes, assigning Adam as male and Eve as female.

The New Testament was surprisingly positive about mixed-gender people, who were at the time called “eunuchs”, which we know encompassed intersex and some other gender non-conforming people in the concept of the ancients:

https://en.wikipedia.org/wiki/Intersex_people_and_religion#Christianity

https://www.hrc.org/resources/what-does-the-bible-say-about-transgender-people

[T]he word “eunuch” in the ancient world would also sometimes be used for those who we would now call intersex. Trans scholars today aren’t interested in these individuals because they believe that eunuchs identified as transgender, but rather because some of the things the eunuchs in scripture experienced are similar to what trans people – and intersex people – experience today, particularly in terms of discrimination, oppression and dehumanization.

Once the people of Israel are freed from captivity, several prophets, including Isaiah, guide them in the rebuilding of their homeland. In Isaiah 56:1-8 God speaks through Isaiah and says that even though Deuteronomy 23 outlawed the participation of eunuchs in Israelite society, in the new Israel they will have a special place–God says, “I will give, in my house and within my walls, a monument and a name better than sons and daughters; I will give them an everlasting name that shall not be cut off” (Isaiah 56:5, NRSV). This wide welcome would have been a relief for the eunuchs, but warring theological factions meant that as far as we know, this prophecy was never fulfilled.

Many years later, Jesus mentions eunuchs in Matthew 19:12, where he notes that there are many kinds of eunuchs, including “eunuchs who have been so from birth,” “eunuchs who have been made eunuchs by others,” and “eunuchs who have made themselves eunuchs for the sake of the kingdom of heaven” (NRSV). While the first group might include intersex people, and the second group people who were castrated by force, Christians have been arguing for centuries about who might be included in that third category. Regardless of whom he was referencing, what we do know is that in this moment, Jesus first of all does not denigrate eunuchs like others in his society may have done, and beyond that he actually lifts eunuchs up as a positive example. The fact that Jesus positively mentions people who are gender-expansive in his own time and place gives hope to many gender-expansive people today.

Finally, we see another important eunuch in Acts 8:26-40 who travels all the way from Ethiopia hoping to worship in the temple in Jerusalem, and who meets Philip, one of Jesus’ followers, on the way home. Up to that point, we don’t have a record of eunuchs becoming part of the early Christian church, but in this story in Acts we hear about this Ethiopian eunuch who, after hearing about Jesus, asks Philip “What is to prevent me from being baptized?” (Acts 8:36, NRSV). While Philip could have said that there was no precedent for this situation–that the Ethiopian’s ethnicity as a non-Israelite or his identity as a eunuch might indeed prevent him–instead, Philip baptizes him with no questions asked and no strings attached. This story of a gender-expansive person of color welcomed as one of the first Christian converts is a powerful part of our spiritual history.