To my (American) ear, "What would most people know about insulin?" is correct, and "What would most people knows about insulin?" is incorrect.
"What would the most people know about insulin?" sounds unnatural. "The most people" is usually used as a superlative, not as a way of referring to a specific group of "most people". "Most people" is deliberately vague as to which people are in the group, so a non-superlative use of "the most people" is usually self-contradictory.
"What is the most people you have ever talked to at the same time?" does sound natural. Notice that this question asks for a superlative -- the result of comparing the sizes of all of the groups of people "you have ever talked to" -- so this use of "the most people" refers to a single group of people. "What is the largest audience you have ever spoken to?" and "What is the largest group of people you have ever talked to?" sound even more natural.
"The most people I have ever talked to was 2,500 people, during a meeting at Town Hall." In this usage, "the most people" is singular.
You shouldn’t think of “kind” as a separate noun here – think of it as part of a noun phrase.
Your sentence can be thought of as:
...which wouldn't be compared to other X
where X functions as a plural noun. So, you could write it as:
...which wouldn't be compared to other jobs
but using a plural noun phrase works fine, too:
...which wouldn't be compared to other types of work
(In that example, we use the singular work, because work in that context is a mass noun.)
Getting back to your examples, you needs to the plural “kinds”:
...which wouldn't be compared to other kinds of jobs.
You can actually omit the “of jobs”, and see which sentence sounds grammatical:
...which wouldn't be compared to other kinds → (okay)
...which wouldn't be compared to other kind → (wrong)
One more interesting fact: you can use a singular noun phrase if you change other to another:
...which wouldn't be compared to another kind of job
Best Answer
You are partially correct. In the sentence "more than half the group," the word "of" is implied, so technically the sentence is "more than half of the group." In the second sentence you provided, you could omit "of," but you would have to include the article "the" (so it would become "more than half the jobs"). The omission of "of" is not specific to singular or plural necessarily. "More than half the pizza" and "more than half the pizzas" are both colloquially correct. To reiterate, the word "of" is implied*, even when it is omitted, and this phenomenon is not specific to plural or singular.
*This omission may have come from Latin, in which the genitive case does not have an auxiliary word meaning "of" like English. English based many of its strange grammar rules off of Latin. This MAY BE one of those instances.
Example of Latin genitive: Filius Dei
Example of English genitive: Son of God