The oceans used to be much lower in salinity, probably fresh or bordering on it. Partly, though, there’s an assumption at work that, since most known lifeforms aren’t halophiles, the halophiles must have arisen from them (rather than the other way around). Eventually this may be settled one way or another by studies of deep sea vents and ocean floor sediments.
It’s not surprising that most species on Earth are not halophiles, since most of the Earth is not extremely salty. Many or most halophiles are classified in Archaea, a domain of life unto itself. It’s speculative to talk about their origins.