The Greek word for firstborn is often transliterated as prototokos (Strong's 4416). It is a compound word derived from the words often transliterated as prótos (Strong's #4413) and tiktó (Strong's #5088). Protos means first and tiktó means to bring forth, as in a begettal.
Prototokos corresponds with forms of the Hebrew word often transliterated as bekor (Strong's #s 1060,1062,1067), which also means the first to be born or brought forth.
None of these forms ever mean never brought forth into existence.