1 or 2:1-2,
1 And I, brethren, when I came to you, came not with excellency of speech or of wisdom, declaring unto you the testimony of God.
2 For I determined not to know any thing among you, save Jesus Christ, and him crucified.
If you read this like you would a newspaper, i.e., read what's written without looking for hidden meanings, I think you would see that Paul told them he couldn't go beyond the crucifixion of Jesus.
1 Cor 2:6-7,
6 Howbeit we speak wisdom among them that are perfect: yet not the wisdom of this world, nor of the princes of this world, that come to nought:
7 But we speak the wisdom of God in a mystery, [even] the hidden [wisdom], which God ordained before the world unto our glory:
"Howbeit" sets this verse in contrast. Although Paul could only preach the basics (not that there is anything wrong with basics) to the Corinthians, there were people who were more "perfect" to whom he could tell more, namely the wisdom of God's mystery.
Chapter 3 gives the reason for this. Basically, the Corinthians were carnal and constantly infighting among themselves.
What you call symbolism would have been perfectly understood by the ancient Jews. They understood the idioms. We can also, but it takes a bit of effort.
In any case, an idiom is understood by those in the culture that uses that idiom. English is full of them and although they are not true to fact, we all agree on what they mean. An idiom does not give anyone the right to make up something. They all mean one thing and those in the culture that created the idiom should understand what the one meaning is. Revelation is no different.
Well, there are those who don't agree with what I write, but with few possible, maybe exceptions, I think I'm pretty clear on what I say. I think the miscommunication is because of the glasses worn by those who read it. Those glasses are colored a certain way and I guess it's hard to be objective when reading through a filter biased against the message to begin with. It can be done, but few are able to read objectively.