The paper you're linking does not support the conclusion you're drawing and I'd encourage you to read it more carefully. Modern humans are omnivores, which means their diet included both animal and plant products, though in different proportions at different times and places.

Moreover, the suggestion that humans started eating meat recently is patently ridiculous in the face of the material record. The nicest way I can put this is to strongly recommend spending some time with Wikipedia. A good starting point would be the stone tools page, in particular the section on the Acheulean industry: https://en.wikipedia.org/wiki/Stone_tool#Mode_II:_The_Acheul...