Believing in a god as a separate entity from humankind is actually a minority belief - even Christianity didn't have it until the 12th century. Until that time, the bible was interpreted as poetic metaphor.
I'm not sure who is teaching you this information, but your statement is not historically correct.
The Hebrews believed in a living, all powerful being, referring to him by various names (YHVH, Abba, Adonai, Elohim, HaKadosh, Meleck Elohim, etc. etc.). Moses saw God's back, https://bible.org/seriespage/29-back...xodus-3318-349
The Jews knew God was a powerful entity, and they feared him, having seen His might and power multiple times. Even the pagans who lived in the areas around the Jews knew the power of their God and feared Him.
Later on, the Christians believe in the Jewish God, and believe that God came to earth as a human being, fully human, fully God as Jesus, to live, and die to atone for our sins, since we were so stinking weak (evil) we couldn't even keep His simple rules. Jesus lived for 33 years, approximately 1200 years before your claim. 1,000's of people saw him.
Flavius Josephus, the Jewish historian born in 37 CE, who was hired by the Romans to keep track of and write their history a few dozen years after the death of Jesus https://en.wikipedia.org/wiki/Josephus
interviewed people who saw Jesus, as well as people who knew people who saw and knew Jesus and he wrote their testimonies in his chronicle for the Romans. Anyone can purchase a copy of Josephus' chronicle today, in their own language.