It is still being used in the Semitic sense. You can have a literalist translation or a literal one. You have to know the audience to understand Scripture, the Aramaic speaking Jews would know what “brother” meant. Greek translation may have been literal translation of Aramaic. We do know Jesus spoke Aramaic, and that was translated into the Greek for the Hellenist Jewish Christian converts. Maybe even a bad translation. But it is what it is, and scholars have to pore over ALL the texts to determine what would have been said. This is not something I could do for myself, even if I were fluent in all three languages. I have to rely on an outside source for this.
The scholarship of the Bible is topic of another thread. If you have access to Hebrew, Aramaic, and Greek texts, and can claim Biblical scholarship, start a thread that addresses this issue.
Catholics rely on the Magesterium. We do not constantly reinvent the wheel to prove things to ourselves that have been hashed out over the centuries. We can read all about it in history.