I would say that you have to understand that whatever we’ll answer now, doesn’t mean it will be same in a year. We just started to switch from OpenPype to AYON. OpenPype tasks were not really considered as entities, so there is massive amount of logic that does not consider tasks as entities. Tasks were used to “create” the product name, or as fill data for templates, but you could operate without them being used. There are workflows where requirement of task is not really necessary, and you might need to integrate new version of the same product from different task. This is how it is, and not sure if we can change that.
On database level, Folder is child of Project or other Folder. Task is child of Folder. Product is child of Folder. Version is child of Product, and can have reference to Task (Optional). Representation is child of Version.
From the named production tracking services, ftrack is the closest to this setup, where the task is optional too.
The database hierarchy is comming from avalon → pype → OpenPype, AYON added the reference to Task on Version, which was not possible before.