Weird once meant the opposite of random. It meant that your life was already decided.
The word starts as the Old English noun wyrd, "fate, chance, destiny." It is built from the verb weorþan, "to come to pass, to become," and the root behind it is a Proto-Indo-European one that Wikipedia glosses as "to twist" and Etymonline as "to turn, to wind." German werden, "to become," is a cousin. The idea runs from turning to becoming to what has become your lot.
Old English poems treat wyrd as inexorable. Beowulf says "Fate goes ever as she shall," and The Wanderer calls it wholly inexorable.
The Old Norse relative is urðr, which means "that which has come to pass." It is also the name of one of the three Norns, who set the laws and decide the lives of humans. The other two are Verðandi and Skuld.
The adjective came from a phrase. Etymonline dates "weird sisters" to about 1400, meaning women with power to control fate. The phrase named the classical Fates and, by extension, the Norns. In Middle English you could say someone was "weirded" when they were predestined.
Shakespeare did not invent the term. Merriam-Webster says he adopted "weird sisters," spelled "weyward" in the play, for the three witches in Macbeth, and that the adjective grew from a reinterpretation of his usage. Wikipedia adds that the Weird Sisters had drifted from their classical roots by the Elizabethan period.
Then the noun fell away. In the early 1800s the adjective lost "sisters" and began to stand alone. Todd's 1818 supplement to Johnson defined it as "skilled in witchcraft." Etymonline says Shelley's Alastor was perhaps the first to use it consistently in print for "supernatural, uncanny," and says the sense "odd-looking, strange" appears around 1820. Merriam-Webster dates the supernatural adjective to 1817.
So the everyday meaning is only about two centuries old. The fate sense had faded by then, and the witches of Macbeth sit between the two meanings.