Though it was never confirmed there is a possibility that Eddie might have been a Mutant prior to gaining The Uni-Power as he demonstrated the ability to sense the demons Gart and Rath being brought into our plane of existence by a pair of foolish young stockbrokers (who oddly enough had the same last name as Eddie but were completely unrelated to him, Eddie's Father Timothy or Eddie's Mother Kendra) before they got loose. Eddie's conflict with Gart and Rath was a relatively short one due to their inherent weakenss to light (Gart and Rath were darkness manipulating demons) and were completely destroyed when Eddie unleashed a "Uni-Nightlight" that engulfed his whole neighborhood in a brilliant light and banished the barrier of darkness that the demons had erected around the neighborhood. Eddie then returned to his crib, sighing sadly as The Uni-Power left him and continued onto its next host, and was praised by his Parents for his victory over Gart and Rath.
It is possible that Eddie might have been born a Mutant as he had demonstrated the ability to detect Demons crossing over into our reality but it was never confirmed. When bonded with the Uni-Power Eddie commanded all of the powers of Captain Universe including flight, super strength and speed, invulnerability, light projection, the ability to transform inanimate objects into living beings and a protective force field.