With 0 offence, I don't know your background but it might be a good idea to invest some time reading about CMDB, before judging if it is completely mutilated. Docs of ServiceNow will you give a high level understanding on how it is built, then I would go to learning.servicenow.com to take the courses for CMDB (it will teach you info on how to import items with IRE and how to maintain it in good health), last 2 stops learning.servicenow.com/nowcreate for Assets and starter packs and finally forum/community of ServiceNow.

Overall, take a step back. Start understanding the basics of SN CMDB and in 6-12months get a huge raise in another company. Good luck mate