well considering your theory isn't a cup yeahi doubt it holds water

The Exo were created to fight the Vex. It's possible that their AI was designed in a similar fashon to the Warmind's so the Vex would be unable to or have difficulty simulating them. It's also possible that theu were given gender for the same reason, to be more diverse and harder to simulate by the Vex. The Exo's Deep Stone Crypt also shares an uncanny resemblance to the Citadel on Venus, suggesting that the Vex have something to do with Exo sentience, it's could be that prolonged exposure to the Vex caused the Exo's systems to advance

Exo's appear to have been created by Clovis Bray. It was Clovis who offered to make Cayde an Exo in exchange for writing off all of his debts. Bray must have got something out of doing so, perhaps Cayde was a test subject for the procedure. There's a small document in the Treasure island book regarding Cayde as an Exo on Clovis Bray paperwork. That's probably what the Exosciences was, the development of Exo's. In the Exo grim it says someone wanted to live forever, that could have been Clovis. At some point Rasputin took over the Exo project. He turned them into weapons. It's unknown how many Exo's were once human. The one's who can become Guardians probably were. Light is the power of life. Maya Sundaresh came to the conclusion that something more solid than the human substrate was needed for their minds to use the ISR device. This was based on Vex gateway technology to allow people to see alternate timelines, and possibly the future. The human mind couldn't take the strain of being forked into different timelines. That could be why Rasputin took over the Exo project. This is why it's likely the Exo stranger is her from our timeline or another.