There was a time that we had a snout like all mammals. But that changed since we started cutting tools from boulders.
When we started doing that, we could not yet talk. We did have warning cries and hum sounds when we did not like something.
More wasn’t necessary, we could perfectly live with that.
But we succeeded to make from stone more and more perfect stone tools and weapons by better techniques, after the hand axes arose knives, arrow- and spearheads. But how could the old generation pass that on to the young?
That did not work anymore with showing only, they started to make gestures and screams, one began to learn to talk.
So one could teach the youth the tricks to make these better tools. And so we went on to gradually build a technical world.
Because of speech the tongue moved deeper into the throat so that we could articulate with the tongue (tongue shaded). Thus we got a flat face.
The emergence of a flat face during the stone age is a strong support for my assumption that speech was created by the need to pass on the increasingly difficult stone techniques