Except when it doesn't. Precedent is overturned all the time. In fact the whole "Selective Incorporation" doctrine arose as a way to overturn the precedent that said that "Privileges and Immunities" of US citizens did not include those protected by the Bill of Rights, but rather uniquely federal things, like the right to use the navigable waterways.
Then there was the case which overturned Texas sodomy laws, (Lawrence v. Texas, 539 U.S. 558 (2003)), which overturned precedent that was less than 2 decades old (Bowers v. Hardwick, 478 U.S. 186 (1986))
I'm not even sure what that means.
Lower courts cannot ignore or overturn binding precedent (see: stare decisis). That's why it's called binding precedent. It is law, as all binding precedent is law. In this case, the appellate court established a precedent which MUST be followed by all subordinate lower courts, or they'll be subject to reversal, just as they'd be subject to reversal if they ignored statutory law.
The Supreme Court can overturn precedent established by any lower court decision (as that precedent wouldn't be binding on superior courts), and/or any precedent that they've (the Supreme Court) previously established, although that is done so rarely, most lawyers can recite from memory the major instances of such reversal.
"Precedent is overturned all the time."
Well, I'm not sure I'd agree with that characterization, but even if I did, that doesn't limit or foreclose binding precedent as law, now does it. Statutory laws "are changed all the time", but does that somehow make them less legal? Of course not.
But, I applaud you and your google law degree for trying.