'Someone' in the Bible

But someone testified somewhere, saying, "What is man, that you remember him, or the son of man, that you care for him?

For every house is built by someone, but the one who built all [things] [is] God.

And someone does not take for himself the honor, but is called by God, just as Aaron also [was].

For indeed, [although you] ought to be teachers {by this time}, you have need of someone to teach you again the beginning elements of the oracles of God, and {you have need of} milk, not solid food.