Some Bible objectors argue that the existence of asexuality in nature proves that sex/gender is fluid and the Bible is wrong about sex/gender being binary. Does what animals do have anything to do with what humans do? The Bible says that humans are designed explicitly as male and female (Gen 1:28, Gen 2:24). There are intersex people, but those are outliers caused by mutations. If every person in the next generation were intersex and potentially sterile because of it, we would be facing potential extinction as a species. Therefore, humans are designed to reproduce sexually, and anything that hinders that is unnatural and against the system God set up for us.
As for animals, the land and flying animals that get on the Ark do so in pairs of male and female (Gen 7:15-16). However, there is no scripture giving exclusivity of sex to any species other than humans. Several land animals, including various types of snails, slugs, and earthworms, are naturally hermaphroditic. More specifically, they are Simultaneous hermaphrodites, which means they have both genitals and can reproduce asexually. Fish sex is never mentioned in the Bible, and hermaphroditism and alternative sex mechanisms are most common amongst sea creatures. Sheephead fish are Protogynous, which means they start as females and certain ones become males at sexual maturity based on dominance. The opposite happens, like in the case of clownfish, which begin as males and later become females based on dominance; they are Protandrous. In addition, seahorses have opposite gender roles (the males get pregnant).
Every creature that’s not asexual requires the two complementary sexes to reproduce. In the case of seahorses, they’re still classified as male and female, respectively, based on the gametes produced. What makes them unique is the role reversal in the process of procreation, because the female lays eggs in the male’s “womb”. Hermaphrodite creatures are born with the ability to either self-reproduce or transition their sex naturally. They don’t need external hormone manipulation and surgery to do so. If a creature can do it naturally, then it’s by design. Humans can’t do these things naturally, so they’re not this way by design. Humans, like most other creatures, reproduce sexually and are not hermaphroditic, meaning they have distinct male and female reproductive systems. Most land creatures reproduce sexually with complementary sexes; the rare exceptions are mainly some mollusks and amphibians. Creatures that have these abilities are a unique exception to the rule.
From a biblical perspective, the existence of alternative sex mechanics like hermaphroditism and asexual reproduction in animals doesn’t apply to humans. The naturalism ideology goes after the credibility of the Genesis account by connecting humans with animals so that the culture can apply new non-binary sex ideas to humans. They suggest that, given the existence of hermaphroditic sea creatures and humans, along with other land creatures that supposedly evolved from these sea creatures, gender fluidity is a natural product of evolution. However, intersexuality (hermaproditism) in mammals, such as humans, is not a mechanism for asexual reproduction; it is a mutation that can cause sterility, thus preventing any evolution through natural selection, as it stops reproduction. Furthermore, the Bible doesn’t support this because it says humans are a special creation made in God’s image (Gen 1:26-27). Jesus died for humans, not animals; therefore, only humans are created in God’s image. Only humans possess a language system that can be spoken, written, and transmitted across space and time with specialized technology that only humans can create. It’s the likeness and image of God that makes us unique. We are not mere animals, nor is our design based on them.
More on the uniqueness of human language here.
More on Evolution in the Bible here.
Resources:
Gender Bending fish
Hermaphrodites