https://www.cidrap.umn.edu/measles/measles-does-long-term-damage-immune-system-studies-show

Clinicians and epidemiologists have long known that measles infection increases childhood morbidity and mortality for as long as 5 years after illness, and measles in the pre-vaccination era was likely associated with at least half of all childhood deaths from infectious diseases.

Non scholarly https://abcnews.go.com/Health/measles-breakthrough-cases-vaccination-important/story?id=120276354

scholarly https://pmc.ncbi.nlm.nih.gov/articles/PMC9413104/

Given 97% efficacy of measles vaccine, how do you explain many countries have had measles elimination for so long?

The tax on non Muslims (jizyah) was in a way beneficial to creating a heterogenous environment. Anybody who tried to expel members of different faiths suffered an immediate loss of income and soon saw the err of their ways. And the more prosperous non-muslims are, the more tax they can pay, so it also gives a reason to take special care of them and help them to prosper.

I don’t think it was really such a big deal back then beyond your kind of baseline drama and conflict humans always get up to. But not much special aminosity between these two groups.

https://en.wikipedia.org/wiki/History_of_the_Jews_under_Muslim_rule

Christians tend towards higher than average belligerence but don’t over generalize from them.