That's not a Hindu belief, and is an overly modern reading of Hindu mythology.

Just like Hindu/Indo-European notions of asparas/wood-nymphs doesn't imply the existence of and rationalization of a tribe of forest women, this isn't really a belief among Hindus about a former state of monkeyhood.

Ancient people simply believed in literally supernatural/estoeric things - they weren't "secretly" technologically advanced with a strange vocabulary we now read as religious.