Spear and Shield: A Few Weeks of Drilling
The spear is the easiest melee weapon to use and was the core armament of all medieval armies. If you want effective troops than you’d actually need them to understand drill. Knowing how to march in step, facing movements, and obeying commands are all critical, and can be learned quite well within 7 weeks. I know this from personal experience, because modern militaries still teach the core essentials of marching.
Although the basics of archery can be picked up in a day, it takes a lifetime to master. It requires significant strength and skill, so much so that we can identify the skeletons of English Longbowmen by their thicker arm bones. Archery was such a valuable skill that requires so much time that there was a law in England for several centuries that mandated the practice of archery on Sunday, a day when all other work was prohibited. Archery can be very effective for a peasant army if it was already an integrated part of their culture, like it was in England or Korea.
Knights started their military training when they were about 12 years old. Effective horsemanship takes years of continual practice to become good at, because you have to know how to control and trust a powerful animal and bring that animal into a brutal fight against other men riding big animals. The knight needs to be skilled enough to ride fast and hard while wearing armor, and once he makes contact he has to be able to fight from atop his horse.
Being a knight also entails using weapons that require much more skill than the common spear or cudgel. Swordsmanship also takes years of effort to become decent at, and fighting in armor is also a skill in of itself, even in the mail hauberks of 1000 AD. (Note: knights in 1000 AD are going to be in chain mail, not plate so they will be using swords kite shields more than maces, hammers or poleaxes.)
Horse Archery: Generations
It takes years to master archery and years to master horsemanship, so you can see where this is going. Horse archery requires a specific set of cavalry skills and advanced archery skills that were available to only available to two kinds of Warrior. The first were elites like samurai who spent their life training like knights, and the second were steppe nomads.
Nomads were such skilled horse archers because they spent literally their entire life preparing for it. They rode horses from an extremely young age and practiced with bows from an extremely young age, and then they practiced horse archery to get all of their wild game.
European peasants as settled farmers just don’t have the ability to do this nor do they even have the right environment. Unless if you’re being generous with what counts as “peasant” because you could have poor nomadic herdsmen in Russia or Ukraine who were vassals to some boyar, but I kind of doubt that’s what you had pictured