But the manifesto was written by many of the same people. The expectation that they would be compatible seems reasonable. And, the "Scrum Alliance" happened very shortly after the manifesto.
But, unfortunately, scrum has become synonymous with "Agile" in the corporate mind. Everything, including SRE and ops work, gets force-fit into Jira "Agile" (really FrAgile) methods and meeting-heavy rituals.
But scrum easily devolves to rapid cycle waterfall death marches. This has been going on for at least nine years that I know of. It sucks.
When a company says "We do Agile with Scrum" I wince and am very, very skeptical.
It's almost like scrum pre-dates the agile manifesto. (Which it does)