Congratulations on your success! However, the ITIL Foundation certification demonstrates that you have base-level knowledge of the concepts of IT service management (ITSM). One of the challenges that the authors of ITIL faced when writing such a complex topic is how to structure ITSM so that people could learn the topic in a series of progressing classes instead of all at once.
The service lifecycle that you learned in the ITIL Foundation course is the first step in the progression of courses in ITSM. As such, the ITIL Foundation course simplifies the complex topics of ITSM into a few-days-long course with an exam at the end. There is no way that 1,000+ pages of the IT Infrastructure Library can be learned in a few days. In fact, this simplified view of ITSM does not provide the necessary guidance to truly reap the benefits of what ITIL can offer an organization.
In the intermediate courses, the service lifecycle is explored in far more detail. As you explore those concepts and gain a full understanding of them, this detail often conflicts with the simple concepts you learned in the ITIL Foundation course.
An interesting side effect of continuing the intermediate and advanced courses is that students come away from the course realizing just how much they didn’t know before the course and how much ITIL Foundation left out.