-
Yes, although 'idiot' goes back a long way, to Ancient Greek, and in its original meaning merely means something like 'someone without a role in public life'.
The word "idiot" comes from the Greek ἰδιώτης, idiōtēs 'a private person, individual', 'a private citizen' (as opposed to an official), 'a common man', 'a person lacking professional skill, layman', later 'unskilled', 'ignorant' from ἴδιος, idios 'private', 'one's own'. In Latin, idiota was borrowed in the meaning 'uneducated', 'ignorant', 'common', and in Late Latin came to mean 'crude, illiterate, ignorant'. In French, it kept the meaning of 'illiterate', 'ignorant', and added the meaning 'stupid' in the 13th century. In English, it added the meaning 'mentally deficient' in the 14th century.
https://en.wikipedia.org/wiki/Idiot
I find it a word with a more neutral etymology that isn't quite as bad as other insults, which, let's face it, all have a lot to do with people being nasty to each other. However, you can't do without insults completely (they're a necessity of life), and the later meaning of 'village idiot' is only one branch of its meaning. I find the original meaning vaguely connected with 'not doing any good (or only good for oneself)' and I use it in roughly that meaning. But simply, you need a word, or words, you can say when you're angry about someone, without inadvertently repeating discriminatory and victimising words like 'moron'.
'Imbecile' was part of the same nasty, discriminatory terminology as 'moron'. It's not in use as widely, though, probably because it's longer and more complicated phonetically. I see the adjective used more often, I think.
So was the driver at Assembly Passage turning into it from Redman's Road when he drove at you? He should obviously have waited to turn until you had completed your manoeuvre. It's an inversion of normal practice, of course, in which usually the driver/rider on the main street should complete their manoeuvre first, and an inversion which, as you imply, he would obviously have observed had you been in a car.
Assembly Passage is definitely one of the oddest streets in London.
Where was the stop sign incident? Stop signs are very rare in the UK, of course, but that makes them all the more important, as they are usually only used where there is a real need for a full stop. I think the only one I'm aware of in Hackney is at the junction of Well Street and Elsdale Street (blind corner, Well Street one-way and narrow, probably a history of lots of prangs). There are probably others, but I'm not a signage headbanger.
Obviously, your own behaviour wasn't above criticism, no matter how understandable, but as your anger has dissipated you can probably see that. Haven't we all done things we're not proud of, etc. Slapping a stranger is assault, whether in the heat of the moment or not. Anger is obviously a perfectly appropriate emotion in this sort of situation, and it is not your fault that the situation occurred, or that you were in two situations like that on the same day. However, to state the obvious, you place yourself at risk of arrest and being charged with assault--probably less so if you're not black (https://www.lfgss.com/conversations/196586/ (and that wasn't even an assault)), but still.
Also, more of a general remark than aimed at you, but 'moron' is originally a nasty term for people with learning disabilities.
https://en.wikipedia.org/wiki/Moron_(psychology)
It is for that 'eugenics' connection alone that I wouldn't use it. At any rate, it's strange to want to insult someone with reference to people with learning disabilities, who are often the sweetest, kindest people you could possibly meet.