How do you nominalize the verb “to be” in regular/casual speech?

I recently discovered the verb である which seems incredibly useful in that it can take verb forms that です cannot, such as であれば、であるのが、or であっています, but everywhere I look online only ever seems to mention である as a sentence final academic/formal way of saying です. What's especially strange to me is that である is not even in the JLPT vocab list, despite seeming to be fundamental to conveying many ideas

So are there multiple functions of である? Or would these structures best be fulfilled by some other grammar? What I most often find is the structure であることがわかる or similar verbs for "knowing something," but this seems to be a very particular meaning that is not simply nominalization of "to be."

I want to write the following sentence: "There's nothing wrong with being a simple person" – with the working idea being 簡単な人であるのが問題ない, but is this now excessively formal if I were to convey this in casual speech?