Nitrogen is present at 78%, about, and in every day life really has no impact on us at all. It is very important to a number of things longer term of course, but not to the extent anyone would notice were it magically to disappear one day, for that day, being replaced by say argon. This is why some underwater breathing mixtures have argon in place of nitrogen with no ill effect.
Oxygen of course is essential short term. Argon at nearly 1% is third most prevalent and basically irrelevant to much of anything.