There's a lot we still don't know about the domestication of the olive, although recent genetic evidence has deepened the understanding we've gotten from archaeological digs.

Here's a good review from 2017 of the current state of research.

Raw cultivated olives are basically inedible today, and wild olives even more so. Even before olives were cultivated in the sense we'd think, wild olives were harvested. We have evidence from 6000 BC that olive oil was being produced and traded by sedentary societies (and it's very telling that some of the oldest pottery we have is already being used to store large quantities of olive oil), but by that point goats and cattle had been domesticated for about 2,000 years, and both of these animals will happily eat wild olives raw. In addition, wild olive trees yield good quality wood. Anyone grabbing a wild olive will quickly realize it's full of oil.

Oils were very important to ancient humans. They could be used to quickly add needed fat to your diet, soothe skin, work leather, protect metal tools, and so on. It beggars belief that humans weren't exploiting wild olive trees to feed livestock, harvest wood, and provide oil for their own needs long before the olive oil trade emerges in the record. Given the usefulness and ubiquity of salt or brine as a preservative, it also beggars belief that someone wouldn't have experimented with eating a brined olive long before they emerge in the record as a food.

Basically: Wild olives, even before domestication and large-scale cultivation, would have been extremely useful and exploited by humans - probably for thousands of years.