> IANAL but isn't any ruling by even a lower court precedent?

"Precedent" can include both binding authority and persuasive authority. Any ruling (and lots of things which aren't rulings, like scholarly treatises), can be persuasive precedent, but trial court decisions are not binding precedent, even in the district of the court that issued them.

Only appellate court decisions are binding precedent, and only (basically) on courts subordinate to court making the decision.