I think three things are very important to know:
People’s health was very precarious. Catching the flu could very well be the death of someone. Studying cadavers for the evolution of medicine was considered a sacrilege by the church. People had no hygiene habits, such as washing their hands and taking a bath, facilitating the circulation of diseases. It was very difficult for an ordinary peasant to pass the age of 40. The infant mortality rate was gigantic, even among the nobility. So much so that often having to generate an heir became a dramatic task.
A very small minority constituted the nobility (barons, counts, dukes, kings etc). This super-restricted social class had armor and weapons for combat. Another small part of the population was part of the church, so it had food and shelter. But the vast majority were peasants who worked for the nobility (or clergy at times) in exchange for protection. These people lived in poverty and ignorance, and when they needed to fight, they usually carried wooden spears or rakes.
It was a period of scientific stagnation. During the approximately 1000 years of the Middle Ages, little progress was made in biology, mathematics and physics. Techniques to work metal advanced a little more, but in Central America, in that same period, there was already a much more evolved medicine and construction techniques.