deadly vs insanely

deadly is an adjective but insanely is not an adjective.

Word	Noun	Adjective	Verb	Adverb
deadly	No	Yes	No	Yes
insanely	No	No	No	Yes

As adverbs, deadly and insanely are synonyms defined as:

Other synonyms of deadly include deucedly, devilishly, madly.

deadly (adjective)	insanely (adjective)
exceedingly harmful
extremely poisonous or injurious; producing venom
involving loss of divine grace or spiritual death
(of a disease) having a rapid course and violent effect
causing or capable of causing death
of an instrument of certain death

deadly (adverb)	insanely (adverb)
(used as intensives) excessively	in an insane manner
as if dead	(used as intensives) excessively