Inventory Management sheet for lower level staff - needs improvement!

I've tried to create an inventory management workbook for lower level staff to use. I will highlight below the current features and the features I need help with! Do let me know if you are able to provide any assistance. Thanks

Current features:
- Staff can click on each item which links to its respective sheet and click on the top left logo which takes it back to Home page
- Staff enters the re-ordered amount (+) or used amount (-) in each item sheet
- The first page is a summary page that links the current balance of each item
- The first page automatically signals (in red) when an item needs to be re-ordered

Need to have:
- Easy way for staff to enter new items to the list themselves (without having knowledge of how to linking sheets on the main page)
- Easier way to input re-ordered amount (+) or used amount (-) on one page instead of continuously linking to other pages
- Prefer to have all this on one page. My gut is that we can use Pivottables. But I'm not sure how and if this is the best way