Yep. It is indeed. Same with the K in knight, which was added for no fucking reason. Sweden also has an island called Öland which means island land.

I think what you said is slightly wrong. Island and isle are both English words that seem to have no ethymological connection. However close semantic relation of "isle" might have cause the introduction of the "s" at some point. Isle itself probably comes from latin "insula". The French still have only one word "Île". Germans have "Eiland" and "Insel".

island [OE] Despite their similarity, island has no etymological connection with isle (their resemblance is due to a 16th-century change in the spelling of island under the influence of its semantic neighbour isle). Island comes ultimately from a prehistoric Germanic *aujō, which denoted 'land associated with water,' and was distantly related to Latin aqua 'water'. This passed into Old English as īeg 'island,' which was subsequently compounded with land to form īegland 'island'. By the late Middle English period this had developed to iland, the form which was turned into island. (A diminutive form of Old English īeg, incidentally, has given us eyot 'small island in a river' [OE].)

Isle [13] itself comes via Old French ile from Latin insula (the s is a 15th-century reintroduction from Latin). Other contributions made by insula to English include insular [17], insulate [16], insulin, isolate [via Italian) [18], and peninsula [16].

Can the UN declare that every school needs to replace Island with Iland?

Now that is the real question.

etymologically the word is made up of "i" and "land", the "s" was added by some idiot in the 15th century. "i" is cognate with "ö" in swedish which simply means "island", so just pull a power move and drop all the other letters completely.

I mean the L. Like in salmon.