[yazaddaruvala]

Words have a special carve out in copyright law / precedent. So much so that a whole other category of Intellectual Property exists called Trademarks to protect special words.

But back to your point “if you were to take the first sentence from a thousand books and use it in your own book”, then yes based on my understanding (I am not a lawyer) of copyright you would be in violation of IP laws.

[basch]

I doubt it would be a violation.

Specifically fair use #3 "the amount and substantiality of the portion used in relation to the copyrighted work as a whole."

A sentence being a copyright violation would make every book review in the world illegal.