American football players tend to have high BMI, but their body fat percentage is probably lower than that of non-athletes with similar BMI, due to being more muscular. However, many of those playing offensive or defensive line still have high body fat percentage, so they may still be (sometimes very) obese by body fat percentage, even though using BMI may significantly overestimate obesity for them.
In terms of younger or lower risk people dying or becoming very sick while older or higher risk people not doing so, perhaps amount of virus in the initial infection matters. Health care workers who work close to the patient’s face may be vulnerable to getting high doses of virus if the patient coughs or sneezes, for example.