the word 'lame', as an informal slang (in your sentences) would refer
to 'uncool' or 'unpleasant' or 'unpreferable'
example: "what a lame idea"
this sentence derives a broader meaning from the formal 'lame' - which implies 'a disability' or 'an impairment'
as a formal noun, the word 'lame' may mean 'disabled' or 'disadvantaged'
example: "the man with the broken leg is a lame"
the same formal meaning also works as an adjective: "the man with the broken leg is lame"