> no license, and seemingly intended to share it freely with the world

No license means you don’t intend to share it “freely”, since you didn’t share any rights. By default, you don’t own things people shared on the internet just because it’s there.

That being said I’ve even seen people with licenses in their repos who get mad when people used their code, there’s just no telling and it’s best to just treat random sources of code as anathema.