Learn English – “Jolly good” meaning “extremely good” in British English

One of our teachers used to say, All men are human but all humans are not men

In general sense Man refers to the masculine gender specifically and Human would refer to both men and women.

And, regarding why HuMAN has man in it, i don't think it is sexist. Because the word Man was initially a gender neutral term, like the present day word, person, but later got changed.

Source : Man was originally gender neutral

To scalp carries an informal, possibly illegal (unauthorised) , connotation that resell does not:

• (Informal.) to resell (tickets, merchandise, etc.) at higher than the official rates.

Thus usage is from the late 19th century from a practice that became popular in the U.S. with long distance train tickets:

Scalp: (Etymonline)

• Meaning "person who re-sells tickets at unauthorized prices for a profit," 1869, American English;earliest reference is to theater tickets, but often used late 19c. of brokers who sold unused portions of railway tickets.

  • [Railways charged less per mile for longer-distance tickets; therefore someone travelling from New York to Chicago could buy a ticket all the way to San Francisco, get out at Chicago and sell it to a scalper, and come away with more money than if he had simply bought a ticket to Chicago; the Chicago scalper would hold the ticket till he found someone looking for a ticket to San Francisco, then sell it to him at a slight advance, but for less than the official price.]

• Perhaps from scalp (v.); scalper was a generic term for "con man, cheater" in late 19c. Or perhaps the connecting sense is the bounty offered for scalps of certain destructive animals (attested in New England from 1703) and sometimes Indians (i.e., having only part of something, but still getting paid). Some, though, see a connection rather to scalpel, the surgical instrument.

Scalping in finance:

• A trading strategy that attempts to make many profits on small price changes. Traders who implement this strategy will place anywhere from 10 to a couple hundred trades in a single day in the belief that small moves in stock price are easier to catch than large ones.

• Traders who implement this strategy are known as scalpers. The main goal is to buy (or sell) a number of shares at the bid (or ask) price and then quickly sell them a few cents higher (or lower) for a profit. Many small profits can easily compound into large gains if a strict exit strategy is used to prevent large losses.

(Investment.com)