comic relief
A parody is a humorous or satirical imitation of a serious type of artwork.
serious
Quiet, serious and humorous sometimes.
Serious yet funny. -Apex
The likely word is the adjective serious (severe, or not humorous)
pun
Fun humorous serious and a great mix of any type of video.
An example of humorous would be when like someone falls of the ground, and people laugh. This could be an example of humorous, or when someone laughs at a very serious situation, and your like bahaha.
The foil to a serious character would be someone who is humorous, light-hearted, or carefree. This contrasting character would bring levity and balance to the serious character's demeanor and actions.
Tone is the attitude that the narrator gives off. Some examples are: sarcastic, serious, ironic, objective, and humorous.
An incident command system may be employed by a police force to manage a serious incident such as a terrorist attck or a major fire or natural disaster.
Many answerers try to be humorous and witty. But some questions require sober and serious answers.