I was driving down the highway one day, and came to a stop. I tried to start out, but the clutch would not engage at all! The clutch is super easy to move up and down, and I can switch through all the gears easily, even if the clutch is not pushed in. I have had no slipping prior to this. Any ideas?

I would check the Axle driver side and make sure it did not come out of the transmission, I've had this happens to me before.

Probably has an original (leaking) slave cyl hose and ran out of fluid.

Our cars come with a needlessly complicated clutch line maze between the clutch master and slave cylinder.

There is a flexible stainless steel clutch line available. It bypasses the whole mess. It attache's directly to the master and slave cyl. It's easy to bleed. Many of us have installed this.