I cannot argue with any of what you said. After the plaques that fell on Mitsrayim (Egypt), the word says that a mixed multitude came out with the children of Israel. Those who chose to worship the God of Israel became part of Israel. Shaul (Paul) was known for bringing gentiles to faith, but I think frogs, boils, darkness and the loss of first born caused many to abandon The king (said to be a god) of Mitsrayim.

The God of creation is the same today, at the time of Shaul and at the time of the Exodus.