This image clearly shows shrapnel from inside out, hardly evidence of a shoot down. Note that counter sinks are always on the outside of skin so you can have flush fastener heads. Also the gray paint color is the outside paint color, the inside is usually green or white primer. This piece clearly looks like a properly spent missle:
Yes, those look like actual cruise missile parts, but there will be the debris from over 100 missiles laying around at the three targets, there is no evidence where this debris was actually collected.
It actually isn't rocket science, there is no rocket in cruise missiles, they use turbofan engines. Considering these missiles are 30 years old and aren't stealth and we've been able to shoot down Russian made missiles since 91, I'd be shocked if Russia couldn't shoot these down. The fact that all three targets were taken out, though, shows their defenses didn't actually work.