As you probably know, the modern names for the two types of charge are positive charge and negative charge. You may be surprised to learn that the names were coined by Benjamin Franklin.
So what is positive and what is negative? It’s entirely up to us! Franklin established the convention that a glass rod that has been rubbed with silk is positively charged. That’s it. Any other object that repels a charged glass rod is also positively charged. Any charged object that attracts a charged glass rod is negatively charged. Thus a plastic rod rubbed with wool is negative. It was only long afterward, with the discovery of electrons and protons, that electrons were found to be attracted to a charged glass rod while protons were repelled. Thus by convention electrons have a negative charge and protons a positive charge.