Sure, the wheel was probably a literal lifesaver for ancient humans, but you can't hunt a boar by sticking a wheel in its side, and you'll have a hard time skinning a pelt from a bear by running a wheel over it. As Crocodile Dundee would say, "That's not a knife."
That's why we come to the blade -- and its iterations as an axe, a knife and so on -- as a breakthrough that literally saves the lives of humans. In fact, new research has shown that stone tools like a blade didn't just allow humans to eat better, wear better protective clothing and make for a good fight scene in "West Side Story." It appears that 1.7 million years ago when tools began to be formed by human ancestors, they actually contributed to the evolution of how our hands work [source: Reardon].
Even before that, early humans were using sharp stone flakes and hand axes to hack at meat. An excavation in the Afar region of Ethiopia led anthropologists to declare in 2012 that human ancestors were using butchering tools nearly 3.4 million years ago [source: Viegas].