The OT is a Jewish text.
Jesus.. a jew..
the NT.. primarily to Jews.. as well as Gentiles.
Also.. in the OT.. you find the likes of Job.. and David believing in Jesus.. why? They both believe in a redeemer.. a saviour.. who can forgive their iniquities.
On top of this who have Jesus referring to Himself as the God of the OT by saying 'I AM...' and 'Your father Abraham rejoiced to see my day'
Who did Abraham see? God! The God of the OT.
Anyway.. the point is.. that the OT texts came before pagan religions.. pagan religions borrowed from the OT.. not the otherway around.
You can tell this by the unadorned.. straight forward accounts of the OT compared to the embellished, mythological, fanciful accounts of pagan beliefs.
In those times... the law of thumb.. was the more straight forward and unadorned a text was.. the more it could be trusted, because legendary development wasn't there.