Theologically and in praxis Judaism and Islam are the brothers and Christianity is a cousin. That’s on everything from strict monotheistic unity, understanding of divine revelation, the overlapping relationship between legal and religious obligations, methods of belonging to the religious group, and the role of the sovereign in community of faith.
Fundamentally, Judaism and Islam are both comprehensively designed to provide structure and governance to a culturally unified religio-political community in a pre-national sense. Christianity’s foundational centuries were spent working out methods on how a non-unified community of belief could survive and accommodate itself while existing within defined political entities, which expressed varying degrees of tolerance to the new group. The concept of “secularism” as it emerged from the world of late antiquity is fundamentally Christian and not shared with Islam or Judaism.
Rex, your experience of Jews as more culturally similar to Christians is just a reflection of Jews as a diaspora people and Jews in the West were shaped by centuries of exchange with Christians. MENA Jews or Ethiopian Jews would strike you as much different, also because of centuries of exchange with Islam or other forms of Christianity.