If it were that easy, everyone would agree and they do not, armies of seriously clever people claiming to take their meaning from the grammatical text are fundamentally opposed on doctrine!
History and culture are important.
A simple example. I relate this not to defend one interpretation or the other, but prove there is a bona fide argument from history and culture.
The bible makes no reference to the fact that the working language of common people was aramaic. So that a lot of the quotations now found in greek scripture must already be translations of the quotes out of aramaic.
Which questions what Jesus actually said in speaking to Peter, which will not have been Petra and Petros, but probably Cepha in both cases, so the distinction between Peter and Large Rock made by protestants is therefore questionable! If it was cepha in both cases, the distinction was made as a wordplay for effect by the translator, not to change the meaning of what is said - those who believe it was aramaic have every right to believe that Peter and Large Rock were one and the same!.
Now please dont argue that particular issue. The point I am making is that regardless of which side of that debate you are on, the debate is partly in history and culture, and why there is a bona fide disagreement now.
Therefore there is a need for authority, and without it you see on this forum many passionately held but mutually exclusive views, all of whom claim they were guided by spirit.
It is a brave man, that says , they are all wrong, I am right, because I have greater wisdom!