It’s also important in proteins as it’s in amino acids (think of the heart, smooth muscle and skeletal muscles, but also in cell and nuclear receptors, transporters - facilitated diffusion, active transport)
In Gram positive (I think) they have nitrogenous sugars in their cell wall (NAG and NAM).
As well as being in DNA they are also in RNA (mRNA, tRNA, rRNA, miRNA, etc)
Can also down the route of the nitrogen cycle where nitrogenous compounds are metabolised (I think) by certain bacteria.
Plants need nitrogen as well as bacteria/eukaryotes
Could mention the Ornithine cycle although I don’t remember it well enough to know if it’d be relevant. I think it removes nitrogen allowing the carbon skeletons to be used for metabolism/storage which is a way of allowing an organism to get more energy from their diet and remove toxic compounds
From there you could argue that it’s more harmful than good as amino groups are toxic to the body and can’t be stored.
Could also argue that the nitrogen in the air is inane and so another atom e.g. oxygen could be seen as more important.