What would the simplest language be like?

This is related to an earlier question about the effects of a very complex language. Instead of simply asking the reverse, I am asking what a very simple language is like.

So, what would happen if we were to reduce a language down to the bare necessities, the crucial framework that is truly needed for a language?

I’m not just talking about simplifying a language, I’m talking about making it almost unnaturally simple. Modern natural languages have very complex rules that were slowly formed and changed over thousands of years. If you really dig deep, you can find countless places where a language is redundant or inconsistent. For example, English usually negates verbs by inserting another helping verb and then negating that verb instead.

What can we remove from a language without restricting its universality? What rules can we make universal in a language?

Do we really need to distinguish between I and me? How many tenses do we need? Do we need to conjugate verbs, or can this be inferred by knowing the subject of the sentence? Do we need contractions? Do we need to distinguish the words he/she/it?

To give you an idea of what sort of extreme simplification I am talking about, consider the Pirahã language. It only has three standard personal pronouns, one for I, one for you (singular), and one for he/she/they. They have managed to do this for many hundreds of years by simply combining them, such as “I you” for we.