How we can understand Hinduism

We have a world where their numerous rivers some Criss crossing each other which end up in the ocean.

Hinduism or Sanatan Dharm is like an Ocean where lot of rivers dispense. Either one can be latched onto these rivers or progress to stay near the ocean. Any which way they are connected to the one or many constituents which fall into the ocean. Moving upstream is a choice till they are connected to riverways with an eventual end point to the ocean. Also, the rivers are controlled by externalities which creates the flow of the river of right from the point of origination - Oceans create clouds by process of evaporation with oceanic winds carrying the moisture causing rains which help in the origination or swell of rivers.

Then there are rivers which have been dammed and not a temporary one but dammed for life with may be a tiny rivulet flowing after the dam. These hold water in the reservoir and condemned to the reservoir. Sometimes these reservoirs become so big and inundate was swathes of areas that they might go into the area of other rivers and obstruct their flow. These are the religions which confirm to books or tablets.

It's important to draw that in the former also there might be smaller dams built which might impact the flow and causing regression in the area (read society). But eventually the unifying force of nature which asks it to confirm to the order as prescribed by the dharma of sustenance of nature will force these dams to break eventually i.e. if not people realize by themselves. The same might be also wrought upon the bigger dams which might cause these big but 'limited' school of thoughts break suddenly. 

The eternal order has its own way of returning balance when limits are crossed.