Did I say foreknew cannot refer to people? Nope. So this post addresses a strawman argument.
Does "knew" always refer to an intimate relationship? Nope. That is what I said. To know something beforehand includes knowledge of people, corporately or individually.
What does "those He foreknew" actually mean?
Romans 8:28-29
And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose. For those whom He foreknew, He also predestined to become conformed to the image of His Son, so that He would be the firstborn among many brothers and sisters;
Thus the phrase refers to those who are called according to His purpose. So the phrase refers to God's knowledge of those who would be called during the age of grace, hence His plan of redemption. And His redemption plan was not only to redeem believers in Christ but also to predestine those redeemed to be conformed to the image of His Son.