Rat big, cat eaten! Ideas for a useful deep-agent protolanguage

I assume here that this is a worthy research program, and that anybody reading this has a minimal degree of interest in it. Lazaridou and Baroni [2020] provide a recent overview of the area. Both on the phylogenetic and on the ontogenetic scale, human language does not appear all at once in fully-formed garb. Most linguists agree that, as a species, we went through a protolanguage stage involving a small set of simple constructions (Bickerton [2014], Brentari and Goldin-Meadow [2017], Hurford [2014], Jackendoff and Wittenberg [2014]). Children definitely pass through fairly systematic protolanguage phases, such as the "two-word" stage (Bloom