Why do people not survive plane crashes? Serious

You rarely hear of anybody surviving and I confess every time I get on a big jet to fly somewhere I often wonder what I would do.

If the plane disintegrates in the air, can you somehow direct yourself using your arms into something soft?

If it hits the ground just before it does, can you somehow jump in the air so you’re not touching any part of it?

What does happen if you were flying in your 45,000 feet in the air, cruising altitude? Do you instantly pass out? Do you freeze? Does it take a while?

Thank you