It happens all the time afaik, for some eras/civilisations artefacts are so rare and far apart that sometimes all it takes is a random skull / art piece / tool to completely break past assumptions. Watching history documentaries make people think we have a pretty good idea of all the events and their respective timelines but for the vast majority of history we have absolutely no fucking idea what was going on

Things like that for example: https://en.wikipedia.org/wiki/Schöningen_spears

> The spears and the place of discovery revolutionized the picture of the cultural and social development of early humans. Previously, Middle Pleistocene hominins, whether Homo heidelbergensis or early Neanderthals, were regarded as simple beings without language who acquired meat by scavenging other carnivore kills or natural deaths. The spears and their correlated finds are evidence of complex technological skills and are the first direct evidence that these humans hunted their prey. The large and swift prey that the Schöningen humans butchered suggests that their technologies and hunting strategies were sophisticated, that they had complex social structures, and had developed some form of communication (language ability). The Schöningen humans therefore likely had cognitive skills such as anticipatory planning, thinking, and acting, some of which had only previously been attributed to modern humans.[46][47] In addition, the spears have played a major role in debates about the origins of throwing.