Clutch disc or Pressure plate isn't the issue, symptom of these wearing out is when you let out the clutch pedal vehicle is slow to move, slipping clutch, but it would be very easy to shift into 1st anytime because clutch is barely grabbing.
Difficulty shifting into 1st when stopped with engine running means clutch is not disengaging, when you press the pedal to the floor master cylinder pushes hydraulic fluid down the hose and into the slave cylinder, slave cylinder expands and pushes on the Pressure plate forks which releases pressure on the clutch disc which was being held against the flywheel by that pressure.
Clutch disc is the only part connected to the transmission.
Rear wheels are connected directly to the transmission.
When you shift gears you need to match Engine RPMs with rear wheel RPMs.
Clutch makes that easier because it disconnects transmission RPMs from Engine RPMs
If transmission is at 0 RPMs, you are stopped, then to shift gears clutch disc must go to 0 RPMs.
If pressure plate forks are not pushed in enough then clutch disc keeps spinning making it hard to put into gear.
Your symptom reads like slave cylinder is not expanding enough to release clutch disc pressure, if clutch disc is spinning at engine RPMs then it can't match transmission RPMs.
So as Vista 4.0 said, you could have low fluid or air in the system.
No it won't hurt it to drive it that way.