what would an academically inclined elf name the set of two-armed, two-legged individualistic-but-also-social creatures to which they themselves also belong? Surely some of his kin would take offense to the idea of being quasi-man.
They would not, because they are not aware of the word "humanoid". Only us, the readers are.
The common attitude (often implicit in less observant readers) is that the fantasy novel is in fact a story about characters which use a different language, and the novel is the "translation" into English. Usually one does not bother actually creating the language, writing in it, then translating (notable exception: Tolkien did, kind of) - they just produce an English text that's supposed to be "what you would get if a good translator had translated it".
It's important to note that the other language is not necessarily English: It may be English in all but name (ie. coincidentally has the same vocabulary and grammar), it may be a language that "coincidentally" evolved similar to English, it may have similar grammar (especially if the author assumes that grammar is genetic and not purely emergent - this is an open question is linguistics), it may be completely alien, and it may even be related to English: For instance I believe Tolkien wrote his books under the pretense that they were events that actually happened in the ancient past of England. Of course, we know what really happened in England's past, but you have to exercise suspension of disbelief. Alternatively you could say something like "thousands of years ago some humans were teleported magically to the fantasy world and they brought Indo-European languages with them".
Anyone who actually has experience with translation knows that it is rarely possible to translate 1:1, there is always room for interpretation, and something will always be lost in translation. I personally do not believe that two people who speak different language are even capable of thinking the same things in every case (this idea has some support in the linguistic research community). In fact, comparing translations of the same text by different authors can be an experience in its own right, as you will note cases where each translator has interpreted a passage in their own way. A great example is the various versions of the Bible (in English).
Fastidious translators, especially if it matters for the text in question, will usually either use the original word as a loanword (typically indicated by italics, eg. saying ramen instead of maccaroni, samurai instead of knight, daimyō instead of liege lord); or will explain the usage with a footnote (eg. "1: a samurai isn't exactly a knight, the differences are so and so, but for the sake of readability I will hereby render it as knight"). There are many examples of this in philosophy books: Because they deal with abstract, difficult to comprehend concepts, it is hard to decide how to render things correctly. Novels are less tricky, but whenever things such as complicated cultural or social mores come into play, it can very easily get very complicated (consider translating French tutoyer, which is a nonsense word in English because the social distinction does not exist - it cannot be translated).
Your best bet is to follow suit: When using humanoid, add a footnote and explain that in the world of whatever, the word used for sentient bipeds is different, and linguistically not related to the word for human. Then say that you will render this word as humanoid in English, because it is the closest available one. You have to then be careful, if you care, to not for instance make puns with "humanoid", or not have characters complain about it being anthropocentric, since, well, it's not in the original.
To invent an original English term that has the qualities you desire (well, you could just take a shortcut and go with elf-like or whatever else) you really have to learn a lot about the development of human language and human natural philosophy, and study how words were coined. Only then will you be able to produce a truly congruent substitute for "humanoid". But once you do that, only those in your audience who are likewise educated will be able to appreciate it - so it is a dubious effort anyway, similar to writing a sci-fi novel with very accurate speculative quantum physics, that is then lost on everyone but the physics professors of the world, of whom maybe 3 will even read your story.