'The Epic of Gilgamesh is an epic poem from ancient Mesopotamia, regarded as the earliest surviving notable literature and the second oldest religious text, after the Pyramid Texts...The first surviving version of this combined epic, known as the "Old Babylonian" version, dates back to the 18th century BC.'
The writing and compiling of the Hebrew Bible are later but also complicated, because the Bible was produced in various stages.
But no scholar says that only Jews drew on earlier sources. There's no such thing as a perfectly original work of art. The Epic of Gilgamesh is drawn in part from older, Sumerian poems, for example.
But I already explained why Christians are especially vulnerable to this kind of objection: Christians take their core narrative to be historical rather than mythical. Therefore, if that narrative is based on earlier myths, exoteric, literalistic Christianity goes down the tubes.
