One of these days I'm going to write a long blog about this. There are many reasons for the differences in spelling and why it is changing and will keep changing.
One reason that yu find so many different spellings in Middle English (ME) is that English, as written tung, had, for all practical purposes, ceased to exist shortly after the Norman-French (NF) Takeover in 1066. When English did start to be written again c1150 - c1175, there was little to nothing to go by. The NF orthography was very different than the Anglo-Saxon/Old English orthography. Often yu will find the NF "ou" substituted for the OE "u". Thus wund became wound (the injury). Thu (þu) became thou (and was said as thu, not thow).
The NF had a rule of not benoting a 'u' before an 'n' or 'm', thus sum, cum, munk, tunge, asf became some, come, monk, tongue, asf. They also added 'ue' where not needed; for byspel: prologue and catalogue. The didn't like a word ending in a 'v' so there are words like give and infinitive whereas the silent e normally indicates that the preceding vowel is long, it doesn't in these cases.
Other French-Latin loving "reformers" actually made things worse. The added the silent b to dout to make doubt to link it to its Latin roots but kept the Old French spelling of colour instead of the Latin color. They added the silent s to iland to make island (not even a Latin word!). They did the same thing to the French ile to make isle.
There were and are regional and dialectal pronunciations that led (and lead) to different spellings. There was, and often still isn't, set orthography. The letter 'y' can be either be a long ī or short ĭ. So in old spellings, yu might see thinking or thynkyng ... like or lyk.
There are pedants who are resistant to even the simplest and very logical changes. There is no justification for although, though, enough, and through. The 'ough' cluster is confusing and unnecessary. Even tho the alt spellings of altho, tho, and thru hav been recommended by various reform panels and hav been around for years (and are preferred by some organizations like the US Army), pedants insist that they are not acceptable in formal writings. Why? On what grounds?
(BTW, I used altho, tho, thru all thru undergraduate and graduate work, the military, and in corporate writings with nary a problem.)
So spelling will keep on changing whether led by free-spellers like me, or by accident but not without vitriolic sniping by pedants.
BTW, if yu think that my changes in spelling hurt yur eyes, try this (it's all English):
All menschli bȋings ar born frie and elyk in wurđinis and ryhts. Đei
ar gifted wiđ riedschip and inwit and schuld behæv tewards òan anuđer
in a mûd ov bruđerhud.