

Religious Jews believe in Jesus as a person that existed. Opinions on him range from very negative to very positive, it’s complex and varied - https://en.wikipedia.org/wiki/Jewish_views_on_Jesus
Possible this guy’s family has a very positive view of Jesus.
Meta don’t need to see your chats to get a lot of value out of WhatsApp.
They can see who you message (the phone number) and from there they can probably ~90% of the time identify who that person is via Facebook/Instagram databases. They can see who you message when, and how often you message them, and what time of day you send and recieve messages - all of that is very valuable to help them create an advertising profile for you.