I'm not going to directly answer your question, but may help you by making some observations. The Document Library sounds messy and badly structured.
Using folders is often deemed to be bad practise in terms of Sharepoint Architecture, sometimes there are reasons for using folders, but generally they are avoided. Try using 'metadata' tagging instead or maybe use choice columns to avoid the need for endless folders.
Have a read here for some ideas on structuring Document Libraries. How to transition from folders to metadata will also help you.
One other observation - what purpose does your Document Library serve? What kind of documents are stored in there? Could it be better to split the document library in to multiple document libraries instead?
I would recommend familiarising yourself and experimenting with
Views in Sharepoint - you can create filters based on your column data. For instance you can create a filter which will filter on the current user name, use the [Me] filter
e.g. Created By = [Me]. To show only documents created by the currently logged on user.
e.g. Department = Finance. This will show only documents tagged as being for Finance.
e.g. Year = 2018. This would show only documents tagged as applying to 2018.