Answer:
The best way to correctly edit the underlined sentence is the following one: There are a lot of people working together to create a song, including songwriters, producers, recording artists, and others.
Explanation:
First of all, the verb<em> to be </em>should be plural because the existential phrase is referring to a plural noun, <em>people</em>. Then, you should always include a comma before "including" when followed by a nonrestrictive, nonessential phrase or clause.