The problem here isn’t just weapons, it’s training and discipline. There are LOTS of ways you can kill an armored man on horseback. You can use spears, lances, projectiles of all sorts, traps, bolas, ropes, hooks, and any number of other things. Theoretically, there’s a hundred ways to knock a man off a horse. You could throw a chair at him. Any number of farm implements could break a galloping horses’s leg like a carrot stick.
The thing is, though, that this sort of close-in warfare requires substantial organization and discipline. If you can get a few hundred guys together and train them, they can fight against mounted knights, but peasants aren’t in the business of training for war.
To get some idea of how difficult this is, imagine if a dozen mounted knights suddenly burst into your office or school, right now, and started lopping off heads, and YOU had to put together a hundred volunteers to defeat them. Think you could do that? Not bloody likely. Your problem won’t be a lack of weaponry, it’ll be a lack of people who aren’t so panicked that they can be organized. Most people will just run like hell, and will be too frightened to be convinced to do anything else. Even if you can get some people together, without any training or discipline they’re going to break and run the first time they get charged - to be charged by a mounted horseman is a terrifying experience. Peasants in the middle ages were no more prepared to go into combat than the jerks you see in the cubicles around you - hell, maybe even less so. At least the jerks you work.go to school with have seen “Braveheart” and aren’t fearful that God will be angry at them for killing their lords.
The death of knights was not so much any specific WEAPON as it was the rise of professional and conscript ARMIES in Europe. The Renaissance brought with it a new professionalization of military endeavour. Men began to apply technology, science, and mass organization to warfare. Right up until the 18th century an armored knight was still stronger than an infantryman; but a knight was terribly vulnerable in the context of an entire BATTLE, because he was facing well-organized, professional armies. Suddenly the infantry were not pseduo-trained rabble; they were disciplined, highly motivated individuals, in the service of a nation-state rather than just the latest feudal lord, who fought cooperatively rather than running and shrieking like girls when things got scary. For a man on horseback, that’s death. If the rabble doesn’t fight together it’s relatively easy to gallop around slicing off melons, but if they stand and oppose you as a group, you’re a dead man.