"What do you suppose that species was like? If apes and humans evolved from the same species, wouldn't skills needed to survive and environments have been the same? I wonder why only humans have mastered the use of fire for survival? Certainly all the apes could have benefited from the use of fire.
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I don't actually know. Perhaps someone else here can point you to fossil remains of the proto-ape. I do know that it was a mammal, and probably an ape-like critter, but more than that I cannot say.
As for the same environment, animals move in search of food, water, and to avoid overcrowding. The proto-ape moved also, no doubt.
Separation is often a trigger for separate species to emerge. Here's how it might work with the proto-ape. Remember, this is just a thought experiment, not a description of the exact process that occurred.
One group of apes lives on the edge of a lake. Another species moves to the edge of a dry, broad savannah with little water available.
As adaptation occurs through random variations in genetics, the group that lives next to the water favors the development of apes that can swim well. These would be able to gather food from the water and escape predators by swimming.
The group that lives next to the savannah might favor apes that can run well in an upright position. These would be able to chase small animals and escape predators.
As evolution proceeds further, and as populations move into different areas or conditions change, more changes take place in both populations through the adaptive process, over many, many generations. At some point, the changes become too large for the two populations to interbreed, thereby creating two new species.
Repeat this separation and adaptation for a few million years and you have chimpanzees and human beings. That's basically how it works.
The question of the use of fire is a completely separate one. Until human beings evolved to a certain intelligence level, they would not have been able to utilize fire for their purposes. Fire is a dangerous thing to most animals, and confining it for use demands human-scale intelligence. Apes other than humans do not use fire because they are incapable of doing so. They don't need it, since their diet of raw food does not require it.
If man is so less suited physically in terms of strength, speed, agility, etc. to survive in the same environment as apes, or other hominids, then how would the fledgling species have managed long enough to discover firs and use it to enhance his survival? It doesn't seem reasonable that the discovery of fire alone could account for man's survival with so much else against him. Nor does it make sense that there would have been an evolutionary advantage for man to develop as he has.