Now for some basic words that we all use all the time, go and do.
Do comes from the Middle English do, the first person of the Old English don, which just means do. It comes from the West Germanic don and earlier, the Proto Indo European dhe-, set or put in place. As for the other tenses, did comes from the Old English dyde, which is a reduplicated syllable (that means a part of the word was doubled)—which was how West Germanic used to make words past tense.
There’s also does, which comes from doth, which became an S because of the Northumbrian dialect of Old English. Done comes from the Old English gedon, which has a bunch of different meanings, including do. Not sure why they dropped the ge- from it. Maybe so it would fit better?
Go comes from the Old English gan, which just means go. Before that it was the West Germanic gaian and Proto Indo European ghe-, release or let go. Funnily enough, go is what’s called a defective verb, which is actually kind of what it sounds like. In grammar terms, defective means that it’s missing some of its forms. You know, like how I can go, but I can’t have goed. Since it was missing a tense, back in Old English used eode, which we lost at some point and replaced with went.
Went used to be a variant past tense/past participle of wend. Somehow it got taken from wend and given to go, and wended became the past tense of wend. For no real reason. What the hell. We could be using eode.
Tony Jebson’s page on the Origins of Old EnglishEncyclopaedia Britannica