Jews and Arabs are the same ethnic group. They're both semitic.

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https://www.britannica.com/topic/Semite

Semite, name given in the 19th century to a member of any people who speak one of the Semitic languages, a family of languages spoken primarily in parts of western Asia and Africa. The term therefore came to include Arabs, Akkadians, Canaanites, Hebrews, some Ethiopians (including the Amhara and the Tigrayans), and Aramaean tribes.

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During the Exodus not all Jews left. Many stayed behind. Centuries later they converted to Islam, and today we know them as Muslims. But they're descendants of the same people who used to be known as biblical Jews.