Notwithstanding I'm skeptical of your claim, being "naturally social" is the entire reason language has evolved. A (very) distant ancestor's nature has no claim on your nature.
> Language doesn’t prove the absence of natural solitude. It just shows we’ve been “pretty social” for a while.
For modern humans it does.
You can't dedicate a huge percentage of your brain to speech and communication in general, and allocate a sizeable percentage of your total energy usage (!) to them, and still be meant to be a solitary species.
Talking about absolute states. Our being social beings doesn't preclude also experiencing solitude or having more or less tendency towards introversion. A solitary nature in this case has a meaning that we also ascribe to certain animals wholesale, because it describes a biologically driven behavior that can't be said of humans.
Presumably we needed to “notice” an orange in a tree before we could point to it. Before you could communicate with signs, you could probably realize something equivalent to “that’s food”, despite not having language yet.
That ancestor probably has some tiny amount of bearing, though possibly negligible.
Language doesn’t prove the absence of natural solitude. It just shows we’ve been “pretty social” for a while.