Most people aren't consuming nearly enough protein. The US recommended daily allowance for an adult male is only 56 grams per day, or 0.8 grams per kilogram of body weight.
https://www.ncbi.nlm.nih.gov/books/NBK56068/table/summarytab...
That is adequate to prevent acute nutritional deficiencies but is way too low for optimal health and athletic performance, especially if you're trying to recover from an injury or build muscle. Older people also need to consume more protein because our digestive systems get worse at taking in protein as we age.
https://peterattiamd.com/donlayman/
Most of us should be eating at least twice the RDA of protein. And not just any protein, but high quality protein with the right ratios of essential amino acids.