Two of the most common small jumping bugs that appear brown or black are springtails and fleas. Springtails and fleas both may appear indoors and are capable of jumping long distances.
Fleas are detrimental to pets and humans due to the biting they perform that causes itching and irritation. Fleas are also capable of transmitting diseases to both pets and humans with their bites.
Springtails, on the other hand, do not bite pets or humans, and spread no diseases. They may appear in large numbers indoors, though, if they've migrated from outdoors. Unlike fleas, which can reproduce indoors and may take advanced treatments to kill permanently, springtails do not reproduce inside, and they are easily disposed of with a vacuum cleaner.