Inventory import depends on the number of sources/stocks that are created on Magento instance in Stores > Inventory > Stocks & Stores > Inventory > Sources.
Case 1. Import to the instance with only one stock and source.
Please use the following fields to update the inventory:
Root Entity
Catalog Inventory Item Entity
Stock ID can be replaced by stock name, if the "Stock Name to Stock ID" modifier is added to the field
Stock status should be either 1 (In Stock) or 0 (Out of Stock). It is also possible to enable 'Replace' modifier to map values from the file to the stock status
Case 2. Import to the instance with multiple stocks/sources
Root Entity
MSI Inventory Source Item Entity