This idea is quite interesting and reveals a common misunderstanding many friends have about antibiotics. All things have two sides, and the notion of boosting immunity by taking amoxicillin for a year might not yield the desired results, and could even backfire.
The invention of antibiotics is undoubtedly a significant advancement for human health. It is because of antibiotics that humans have a truly effective "weapon" against bacterial infections, leading to a significant decrease in mortality rates due to bacterial infections, thus improving overall human health and life expectancy.