I had known simp from tales of carnies (in carnie slang it was used for the suckers who lose money on rigged games) and so when I first saw it on Reddit as used by frustrated males, it was easy to make the connection. See etymology 1 at Wiktionary[0] with a first attestation from 1903!
The people who know only the contemporary meaning must be orders of magnitude larger than those who knew the early 20th century word, though.
Etymologically, probably, but its most specifically, in its current popular use, about a person with a strong parasocial attachment to someone else, particularly one that is sexually-tinged.
Very commonly used to describe relationships of devoted followers to social media figures.
Etymologically, it might be - it's not really clear. But the meaning is "to be (excessively) subservient to a person or cause" / "someone who is [...]". So a simp/simping is (an accusation of) being (excessively) in favor of a person or cause, such as simping for a character, an idol, a real person, or a political party. Especially used for men who praise a certain woman over and over.
IIRC it used to be but it kind of got mutated as people specifically called men who fawn over uninterested women simps until it was exclusively used for that case and similar. I wonder if other pieces of slang used to be broader than they are now.
