The Christian Bible says that. But it’s just because a later work retrofits a character from an earlier work without regard to the actual development or original purpose of the source material, not because any of it is actually true.
The book of Genesis is itself a reworking of an earlier source. So why prioritise the reworking of the story by the compiler of Genesis over the reworking of the story by the compilers of the Bible?
What do you mean by “actually true”? We can only interpret the story in a context, whether you pick an early Jewish context, or a later Christian context, those are interpretive choices. We don’t have access to the story in its original form, so it’s not as if you can claim a pristine original that must be sacrosanct. One contextual reading is not “actually true”, and the other “false”. They are both narratives and make sense in their own terms. Unless you are arguing that there really was a snake in an actual garden of Eden and that one interpretation is closer to that reality than another, and therefore “actually true”. I can’t imagine that’s what you mean.