Yes, but maybe there was only ever one species, and the idea of other species is itself a misunderstanding.
One can find a bit of bone and claim it is 'Neanderthal' but how can you or I really know this? We cannot. Can one really look at a piece of bone and then gauge how intelligent a creature was from that? No again.
And then, think of the need in science for this type of evidence. Think of the desire for some people to find fame and fortune with their 'discoveries'. Think also of the impossibility in verifying these sorts of potentially false claims - these claims cannot be falsified; there is no test to confirm or deny.
Putting it together, one can also see all sorts of reasons for these sorts of claims to be created and allowed to stand, regardless of the quality of evidence.
To me, with 'Neanderthals', we are in the realm of conjecture. These are ideas. They might be ideas that are faithful to the evidence, well-intentioned attempts at a best explanations... Or they might be a fabrication that arose out of a desire to complete a backstory. However, if we want to speak truthfully, we need to bear in mind that we can never know if these ideas accurately depict history. It doesn't matter if there are whole subjects in academia on the topic, and books etc that assume these ideas to be true - we cannot treat these ideas as facts.