Here is the first of many posts on Runic systems and their history, lore, meanings and uses. Please note that I am not an expert on Runes and I also do not have any academic education in their history. These posts are just a compilation of books, websites and academic papers that I have read through and broken down into separate subjects 
According to Norse Mythology the origins of the Runes came from Odin who hung himself from Yggdrasil, offering himself to himself, for nine days and nights to acquire the wisdom of the Runes, found in stanzas 138-145 of The Havamal
In my research for this post I came across other Runic Systems that seem to have close correlations to the Elder Futhark. Each ranging in region, architecture and time period:
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Gothic Runes
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Anglo-Saxon Futhorc
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Younger Futhark
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Hungarian Runes
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Turkic (Orkhan) Runes
You can find out more about each Here
The Elder Futhark seem to be the earliest known Runic System used widely throughout Scandinavia starting from around 200 B.C.E while the rest came later and spread over much wider areas, some as far as North America.
Here are a couple of paragraphs from the book Futhark: A Handbook of Rune Magic by Edred Thorsson on the origins of The Runes:
“These shapes are ultimately born from the holy signs conceived in the minds of Bronze Age preists and magicians ( and probably much earlier) as abstract expressions of the innermost workings of their religious and magical teachings. They are found in great abundance on the most ancient rock carvings of Scandinavia.”
“The Runic System may well have been fully developed by as early as 200 B.C.E. It is certain that the magico-religious practices of the ancient Germanic people’s were aided by the use of many Runic and/or Pre-Runic signs, do we still have these etched into stone all over Scandinavia.”
“This book deals more or less exclusively with the system of the Elder Futhark, which was the rule between 200 B.C.E and 800 C.E. However, the other two systems are magically valid. The Younger Futhark began to be developed in the seventh century C.E and this development was complete by 800 C.E. The Anglo-Saxon Futhorc survived untill the 10th century C.E.”
And a paragraph from Viking Language 1: Learn Old Norse, Runes and Icelandic Sagas by Jesse L Byock:
" Runes: Runic inscriptions are the second of the two major groups of native sources for learning the language and history of the Viking Age. Runes were an alphabetical writing system. The letters are made from short straight strokes carved on wood, bone, bark, wax tablets and stone. Sometimes Runes were engraved, inlaid, or etched onto steel objects such as swordblades. At other times they were carved on household artefacts such as spindle whorl and bone combs. Many of the longer inscriptions were carved as memorials on stone."
Examples of Runic Inscriptions throughout history:
Oldest Known Runic Inscription
List of Rune Stones in Scandinavia
Runic Inscriptions stock library
As you can see the history of the Runes is a long one of mystery, magic and writings that still hasnt been fully understood in this era. There also isn’t solid evidence that the Runes were regularly used for divination in the earliest periods of Rune use, this seems to be a younger concept based on the magical purposes and meanings of the Runes. Because each Rune holds its own meaning and magical abilities they can be turned into tools of divination for the right practitioner
I’m going to link the websites I used to help me research this topic, there is quite a lot of information on each website and I couldnt fit at all in one post
Database of inscriptions:
Scandinavian Runic Text Database
This website has acedemic papers on a wide range of subjects, but if you type elder futhark, Runic systems or Germanic Runes into the search bar it will narrow the search down for you:
Academia.edu
And a website for Viking age archeology in Europe:
Viking Archeology Europe
Blessed Be
Gosh, so many different runes to explore- there really is so much to learn about runes, their history, and rune magick! 
I’ll be taking notes in my rune journal!!!
I’m always looking for more information in the Runes. I think your right though they seem to have started out as a writing system and grew over time in magical purposes and divination tools