According to the Atlantic, Kolodny's thesis is that toolbuilding laid the groundwork for the development of language.
How about other human behaviors such as group activities requiring coordination and planning, or language as a means to invoke and control specific emotions in others?
Certainly activities such as building encampments, changing encampments, delegation of tasks, coordination during hunting and gathering, all these also required sequenced actions.
Fast forward to the present, and toolmakers are generally below the topmost pinnacle of society; MIT's endowment is only 13 billion compared to Harvard's 35 billion (humor intended).
Dogs and chimps seem to enjoy hearing, learning, being influenced, and being told what to do via language, yet aren't capable of speaking it. Surely pre-modern humans were the same, leaving open a huge selective advantage for the development of vocal/language skills.