found the reason: the original function of the dependencyManagement node in pom is to manage the version only, not to actually introduce jar!
so, of course, the introduction we added to the parent pom.xml will not be introduced, so when I add something such as:

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

was introduced immediately, alas, it was caused by unfamiliarity with maven!

reference: dependencyManagement meaning in Maven