The genus Homo was separated from the Pan genus (chimpanzees) around 7 million years ago. The Hominidae (group that includes chimpanzees, gorillas, humans, and orangutans) separated from the Hylobatidae genus around 18 million years ago, you can go back further until you reach the first tiny mammal, the point is, humans may be a final product, but we have been evolving for quite a long time as well! In the 200 million years of dinosaur evolution they went from incredibly tiny reptile like creatures, to the most massive animals that ever walked the earth. At the same time others were evolving to be faster, smarter, and eventually grew feathers and took to the skies. That is a whole lot of evolving right there!!

the fact that the entire genus went extinct, apart from the birds, is indicative of a turn-over in the environment which they were not able to ‘weather’ – among these factors: the emergence of deccan trap volcanism , which resulted in massive global warming, and a lack of adaptation by dinosaur herbivores to the rise of angiosperms (flowering plants)

at any rate, had their food-chain, and consequently their predators survived, it is unlikely that mammals would have evolved into larger competing forms – hence no higher primates/apes/men.

all this sort of goes along with the concept of punctuated-equilibrium. they hung together, died together, and mammals inherited the depopulated world, in time undergoing their own wave of adaptive radiation. we will similarly hang together, though the extent of our adaptation & adaptability, as a class, is considerably broader then that of our predecessors, imo.

but a big enough meteor could wipe us out, too. no reason for it not to happen, either. without doubt, at some point in the future – climactically or otherwise – a hard rain will fall upon the existing world order, the likes of which have never been seen in human memory.

they will live in interesting times then, as best they can. if they can.