1991 Jeep Wrangler Jeep moves even when clutch is fully dep

I keep my Jeep garaged for most of the year, using it mainly as a recreational vehicle in warm weather. I got it out of the garage this spring and noticed it was harder to put in gear than I had recalled. If I tried to put it in reverse, it would grind unless I put it in reverse when the engine was turned off, then started with the clutch depressed and the transmission in reverse. At several red lights, when I stopped, I could not get the Jeep into first when the light turned green unless I turned the engine off and started in first gear. I noticed when I went to put the Jeep back in the garage that even when the clutch was fully depressed, it was still moving forward, and the same for reverse...with clutch fully depressed, it still moves. Any idea what's wrong? Thanks!