Arrows are just a conceptual tool. And they can be bidirectional. There is no explicit hierarchy, as far as I know.
I’m going to close this thread for being duplicates. And yes, please follow the template and make sure you search first before posting in FR.
This is a somewhat related FR regarding hiding “children”. Collapsing groups. Canvas: collapsable groups
This is a duplicate regarding color hotkeys. [With demo] Canvas: Hotkeys for adding items, navigating and changing color
Thanks