A species (at least in the mammal sense) by definition is discrete, as it refers to organisms capable of producing fertile offspring. This is why dog breeds (which exist on a continuum are not different species.
In terms of speciation (chimpanzees or their ancestors giving rise to humans) this usually occurs due to an event such as a seperation between groups of the same species. They are then subject to differing external pressures as they may live in isolation, and their genetics continue to diverge until they are so far apart that they can no longer procreate and have become a species.
In terms of speciation (chimpanzees or their ancestors giving rise to humans) this usually occurs due to an event such as a seperation between groups of the same species. They are then subject to differing external pressures as they may live in isolation, and their genetics continue to diverge until they are so far apart that they can no longer procreate and have become a species.